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1.1 root 1: .ds OK [\|
2: .ds CK \|]
3: .ds ' \s+4\[email protected]@\'\[email protected]@\s-4
4: .ds ` \s+4\[email protected]@\`\[email protected]@\s-4
5: .de P
6: .br
7: ..
8: .TH KSH 1
9: .SH NAME
10: ksh \- Korn shell, the not standard command programming language
11: .SH SYNOPSIS
12: .B ksh
13: [
14: .B \-acefhikmnorstuvx
15: ] [
16: .B \-o
17: option ] .\|.\|.
18: [ arg .\|.\|. ]
19: .br
20: .SH DESCRIPTION
21: .I Ksh\^
22: is a command programming language
23: that executes commands read from a terminal
24: or a file.
25: .I Rsh\^
26: is a restricted version of the standard command interpreter
27: .IR sh ;
28: it is used to set up login names and execution environments whose
29: capabilities are more controlled than those of the standard shell.
30: See
31: .I Invocation\^
32: below
33: for the meaning of arguments to the shell.
34: .SS Definitions.
35: A
36: .I metacharacter\^
37: is one of the following characters:
38: .RS
39: .PP
40: \f3; & ( ) \(bv < > new-line space tab\fP
41: .RE
42: .PP
43: A
44: .I blank\^
45: is a
46: .B tab
47: or a
48: .BR space .
49: An
50: .I identifier\^
51: is a sequence of letters, digits, or underscores
52: starting with a letter or underscore.
53: Identifiers are used as names for
54: .IR aliases ,
55: .IR functions ,
56: and
57: .IR "named parameters" .
58: A
59: .I word\^
60: is a sequence of
61: .I characters\^
62: separated by one or more non-quoted
63: .IR metacharacters .
64: .SS Commands.
65: A
66: .I simple-command\^
67: is a sequence of
68: .I blank\^
69: separated words
70: which may be preceded by a parameter assignment list.
71: (See
72: .I Environment\^
73: below).
74: The first word specifies the name of the command to
75: be executed.
76: Except as specified below,
77: the remaining words are passed as arguments
78: to the invoked command.
79: The command name is passed as argument 0
80: (see
81: .IR exec (2)).
82: The
83: .I value\^
84: of a simple-command is its exit status
85: if it terminates normally, or (octal) 200+\f2status\^\fP if
86: it terminates abnormally (see
87: .IR signal (2)
88: for a list of
89: status values).
90: .PP
91: A
92: .I pipeline\^
93: is a sequence of one or more
94: .I commands\^
95: separated by
96: .BR \(bv .
97: The standard output of each command but the last
98: is connected by a
99: .IR pipe (2)
100: to the standard input of the next command.
101: Each command is run as a separate process;
102: the shell waits for the last command to terminate.
103: The exit status of a pipeline is the exit
104: status of the last command.
105: .PP
106: A
107: .I list\^
108: is a sequence of one or more
109: pipelines
110: separated by
111: .BR ; ,
112: .BR & ,
113: .BR && ,
114: or
115: .BR \(bv\|\(bv ,
116: and optionally terminated by
117: .BR ; ,
118: .BR & ,
119: or
120: .BR \(bv& .
121: Of these five symbols,
122: .BR ; ,
123: .BR & ,
124: and
125: .BR \(bv&
126: have equal precedence,
127: which is lower than that of
128: .B &&
129: and
130: .BR \(bv\|\(bv .
131: The symbols
132: .B &&
133: and
134: .B \(bv\|\(bv
135: also have equal precedence.
136: A semicolon
137: .RB ( ; )
138: causes sequential execution of the preceding pipeline; an ampersand
139: .RB ( & )
140: causes asynchronous execution of the preceding pipeline (i.e., the shell does
141: .I not\^
142: wait for that pipeline to finish).
143: The symbol
144: .B \(bv&
145: causes asynchronous execution of the preceding command or pipeline
146: with a two-way pipe established to the parent shell.
147: The standard input and output of the spawned command
148: can be written to and read from by the parent Shell
149: using the
150: .B \-p
151: option of
152: the special commands
153: .B read
154: and
155: .B print\^
156: described later.
157: Only one such command can be active
158: at any given time.
159: The symbol
160: .B &&
161: .RB (\| \(bv\|\(bv \^)
162: causes the
163: .I list\^
164: following it to be executed only if the preceding
165: pipeline
166: returns a zero (non-zero) value.
167: An arbitrary number of new-lines may appear in a
168: .I list,\^
169: instead of semicolons,
170: to delimit commands.
171: .PP
172: A
173: .I command\^
174: is either a simple-command
175: or one of the following.
176: Unless otherwise stated,
177: the value returned by a command is that of the
178: last simple-command executed in the command.
179: .TP
180: \f3for\fP \f2identifier\^\fP \*(OK \f3in\fP \f2word\^\fP .\|.\|. \*(CK \f3do\fP \f2list\^\fP \f3done\fP
181: Each time a
182: .B for
183: command is executed,
184: .I identifier\^
185: is set to the next
186: .I word\^
187: taken from the
188: .B in
189: .I word\^
190: list.
191: If
192: .BI in " word\^"
193: \&.\|.\|.
194: is omitted, then
195: the
196: .B for
197: command executes the \f3do\fP \f2list\^\fP once for each positional parameter
198: that is set
199: (see
200: .I "Parameter Substitution\^"
201: below).
202: Execution ends when there are no more words in the list.
203: .TP
204: \f3select\fP \f2identifier\^\fP \*(OK \f3in\fP \f2word\^\fP .\|.\|. \*(CK \f3do\fP \f2list\^\fP \f3done\fP
205: A
206: .B select
207: command prints on standard error (file descriptor 2), the set of
208: .IR word s,
209: each preceded by a number.
210: If
211: .BI in " word\^"
212: \&.\|.\|.
213: is omitted, then
214: the
215: positional parameters
216: are used instead
217: (see
218: .I "Parameter Substitution\^"
219: below).
220: The
221: .SM
222: .B PS3
223: prompt is printed
224: and a line is read from the standard input.
225: If this line consists of the number
226: of one of the listed
227: .BR word s,
228: then the value of the parameter
229: .I identifier\^
230: is set to the
231: .I word\^
232: corresponding to this number.
233: If this line is empty the selection list is
234: printed again.
235: Otherwise the value of the parameter
236: .I identifier\^
237: is set to
238: .BR null .
239: The contents of the line read from standard input is
240: saved in
241: the parameter
242: .SM
243: .BR REPLY.
244: The
245: .I list\^
246: is executed for each selection until a
247: .B break\^
248: or
249: .I end-of-file\^
250: is encountered.
251: .TP
252: \f3case\fP \f2word\^\fP \f3in\fP \*(OK \f2pattern\^\fP \*(OK \(bv \
253: \f2pattern\^\fP \*(CK .\|.\|. \f3)\fP \f2list\^\fP \f3;;\fP \*(CK .\|.\|. \f3esac\fP
254: A
255: .B case
256: command executes the
257: .I list\^
258: associated with the first
259: .I pattern\^
260: that matches
261: .IR word .
262: The form of the patterns is
263: the same as that used for
264: file-name generation (see
265: .I "File Name Generation\^"
266: below).
267: .TP
268: \f3if\fP \f2list\^\fP \f3then\fP \f2list\^\fP \*(OK \
269: \f3elif\fP \f2list\^\fP \f3then\fP \f2list\^\fP \*(CK .\|.\|. \
270: \*(OK \f3else\fP \f2list\^\fP \*(CK \f3f\&i\fP
271: The
272: .I list\^
273: following \f3if\fP is executed and,
274: if it
275: returns a zero exit status, the
276: .I list\^
277: following
278: the first
279: .B then
280: is executed.
281: Otherwise, the
282: .I list\^
283: following \f3elif\fP
284: is executed and, if its value is zero,
285: the
286: .I list\^
287: following
288: the next
289: .B then
290: is executed.
291: Failing that, the
292: .B else
293: .I list\^
294: is executed.
295: If no
296: .B else
297: .I list\^
298: or
299: .B then
300: .I list\^
301: is executed, then the
302: .B if
303: command returns a zero exit status.
304: .TP
305: .PD 0
306: \f3while\fP \f2list\^\fP \f3do\fP \f2list\^\fP \f3done\fP
307: .TP
308: \f3until\fP \f2list\^\fP \f3do\fP \f2list\^\fP \f3done\fP
309: .PD
310: A
311: .B while
312: command repeatedly executes the
313: .B while
314: .I list\^
315: and, if the exit status of the last command in the list is zero, executes
316: the
317: .B do
318: .IR list ;
319: otherwise the loop terminates.
320: If no commands in the
321: .B do
322: .I list\^
323: are executed, then the
324: .B while
325: command returns a zero exit status;
326: .B until
327: may be used in place of
328: .B while
329: to negate
330: the loop termination test.
331: .TP
332: \f3(\fP\f2list\^\fP\f3)\fP
333: .br
334: Execute
335: .I list\^
336: in a separate environment.
337: Note, that if two adjacent open parentheses are
338: needed for nesting, a space must be inserted to avoid
339: arithmetic evaluation as described below.
340: .TP
341: \f3{ \fP\f2list\^\fP\f3;}\fP
342: .br
343: .I list\^
344: is simply executed.
345: Note that
346: .B {
347: is a
348: .I keyword\^
349: and requires a blank
350: in order to be recognized.
351: .TP
352: .PD 0
353: \f3function\fP \f2identifier\^\fP \f3{\fP \f2list\^\fP \f3;}\fP
354: .TP
355: \f2identifier\^\fP \f3() {\fP \f2list\^\fP \f3;}\fP
356: .PD
357: Define a function which is referenced by
358: .IR identifier .
359: The body of the function is the
360: .I list\^
361: of commands between
362: .B {
363: and
364: .BR } .
365: (See
366: .I Functions\^
367: below).
368: .TP
369: \f3time \fP\f2pipeline\^\fP
370: .br
371: The
372: .I pipeline\^
373: is executed and the elapsed time as well as
374: the user and system time are printed on standard error.
375: .PP
376: The following keywords
377: are only recognized as the first word of a command
378: and when not quoted:
379: .if t .RS
380: .PP
381: .B
382: .if n if then else elif fi case esac for while until do done { } function select time
383: .if t if then else elif fi case esac for while until do done { } function select time
384: .if t .RE
385: .SS Comments.
386: A word beginning with
387: .B #
388: causes that word and all the following characters up to a new-line
389: to be ignored.
390: .SS Aliasing.
391: The first word of each command is replaced by the text of an
392: .B alias
393: if an
394: .B alias
395: for this word has been defined.
396: The
397: first character of an
398: .B alias
399: name can be any printable character,
400: but the rest of the characters
401: must be the same as for a valid
402: .IR identifier .
403: The replacement string can contain any
404: valid Shell script
405: including the metacharacters listed above.
406: The first word of each command of the
407: replaced text will not be tested for additional aliases.
408: If the last character of the alias value is a
409: .I blank\^
410: then the word following the alias will also be checked for alias
411: substitution.
412: Aliases can be used to redefine special
413: builtin commands but cannot be used to redefine
414: the keywords listed above.
415: Aliases can be created, listed, and exported with the
416: .B alias
417: command and can be removed with the
418: .B unalias
419: command.
420: Exported aliases remain in effect for sub-shells
421: but must be reinitialized for separate invocations
422: of the Shell (See
423: .I Invocation\^
424: below).
425: .PP
426: .I Aliasing\^
427: is performed when
428: scripts are read,
429: not while they are executed.
430: Therefore,
431: for an alias to take effect
432: the
433: .B
434: alias
435: command has to be executed before
436: the command which references the alias is read.
437: .PP
438: Aliases are frequently used as a short hand for full path
439: names.
440: An option to the aliasing facility allows the value of the alias
441: to be automatically set to the full pathname of
442: the corresponding command.
443: These aliases are called
444: .I tracked
445: aliases.
446: The value of a
447: .I tracked
448: alias is defined the first time the identifier
449: is read and becomes undefined each time
450: the
451: .SM
452: .B PATH
453: variable is reset.
454: These aliases remain
455: .I tracked
456: so that the next
457: subsequent reference will redefine the value.
458: Several tracked aliases are compiled into the shell.
459: The
460: .B \-h
461: option of the
462: .B set
463: command makes each command name which is an
464: .I identifier\^
465: into a tracked alias.
466: .PP
467: The following
468: .I exported aliases
469: are compiled into the shell
470: but can be unset or redefined:
471: .RS 20
472: .PD 0
473: .TP
474: .B "echo=\(fmprint \-\(fm"
475: .TP
476: .B "false=\(fmlet 0\(fm"
477: .TP
478: .B "functions=\(fmtypeset \-f\(fm"
479: .TP
480: .B "history=\(fmfc \-l\(fm"
481: .TP
482: .B "integer=\(fmtypeset \-i\(fm"
483: .TP
484: .B "nohup=\(fmnohup \(fm"
485: .TP
486: .B "pwd=\(fmprint \- $\s-1PWD\s+1\(fm"
487: .TP
488: .B "r=\(fmfc \-e \-\(fm"
489: .TP
490: .B "true=\(fm:\(fm"
491: .TP
492: .B "type=\(fmwhence \-v\(fm"
493: .TP
494: .B "hash=\(fmalias \-t\(fm"
495: .PD
496: .RE
497: .SS Tilde Substitution.
498: After alias substitution is performed, each word
499: is checked to see if it begins with an unquoted
500: .BR \(ap .
501: If it does, then the word up to a
502: .B /
503: is checked to see if it matches a user name in the
504: .B /etc/passwd
505: file.
506: If a match is found, the
507: .B \(ap
508: and the matched login name is replaced by the
509: login directory of the matched user.
510: This is called a
511: .I tilde
512: substitution.
513: If no match is found, the original text is left unchanged.
514: A
515: .B \(ap
516: by itself, or in front of a
517: .BR / ,
518: is replaced by the value of the
519: .B
520: .SM HOME
521: parameter.
522: A
523: .B \(ap
524: followed by a
525: .B +
526: or
527: .B \-
528: is replaced by the value of
529: the parameter
530: .B
531: .SM PWD
532: and
533: .B
534: .SM OLDPWD
535: respectively.
536: .PP
537: In addition, the value of each
538: .I "keyword parameter"
539: is checked to see if it begins with a
540: .B \(ap
541: or if a
542: .B \(ap
543: appears after a
544: .BR : .
545: In either of these cases a
546: .I tilde
547: substitution is attempted.
548: .SS Command Substitution.
549: The standard output from a command enclosed in
550: a pair of grave accents (\^\f3\*`\^\*`\fP\^) may be used as part or all
551: of a word;
552: trailing new-lines are removed.
553: The command substitution
554: \^\f3\*`\^cat file\^\*`\fP\^
555: can be replaced by the equivalent but faster
556: \^\f3\*`\^<file\^\*`\fP\^.
557: Command substitution of most special commands
558: that do not perform input/output redirection are
559: carried out without creating a separate process.
560: .SS Parameter Substitution.
561: A
562: .I parameter\^
563: is an
564: .IR identifier ,
565: a digit,
566: or any of the characters
567: .BR \(** ,
568: .BR @ ,
569: .BR # ,
570: .BR ? ,
571: .BR \- ,
572: .BR $ ,
573: and
574: .BR !\\^ .
575: A
576: .I named parameter\^
577: (a parameter denoted by an identifier)
578: has a
579: .I value\^
580: and zero or more
581: .IR attributes .
582: .I Named parameters \^
583: can be assigned
584: .I values\^
585: and
586: .I attributes
587: by using the
588: .B typeset\^
589: special command.
590: The attributes supported by the Shell are described
591: later with the
592: .B typeset\^
593: special command.
594: Exported parameters pass values and attributes to
595: sub-shells but only values to the environment.
596: .PP
597: The shell supports a limited one-dimensional array facility.
598: An element of an array parameter is referenced by a
599: .IR subscript .
600: A
601: .I subscript\^
602: is denoted by a
603: .BR [ ,
604: followed by an
605: .I arithmetic expression\^
606: (see Arithmetic evaluation below)
607: followed by a
608: .BR ] .
609: The value of all
610: subscripts must be in the
611: range of
612: 0 through 511.
613: Arrays need not be declared.
614: Any reference to a named parameter
615: with a valid subscript is
616: legal and an array will be created if necessary.
617: Referencing an array without a subscript
618: is equivalent to referencing the first element.
619: .PP
620: The
621: .I value\^
622: of a
623: .I named parameter\^
624: may also be assigned by writing:
625: .RS
626: .PP
627: .IB name = value\^\|
628: \*(OK
629: .IB name = value\^
630: \*(CK .\|.\|.
631: .RE
632: .PP
633: .PD 0
634: If the integer attribute,
635: .BR \-i ,
636: is set for
637: .I name\^
638: the
639: .I value\^
640: is subject to arithmetic evaluation as described below.
641: .PP
642: Positional parameters,
643: parameters denoted by a number,
644: may be assigned values with the
645: .B set\^
646: special command.
647: Parameter
648: .B $0
649: is set from argument zero when the shell
650: is invoked.
651: .PP
652: The character
653: .B $
654: is used to introduce substitutable
655: .IR parameters .
656: .TP
657: \f3${\fP\f2parameter\^\fP\f3}\fP
658: The value, if any, of the parameter is substituted.
659: The braces are required when
660: .I parameter\^
661: is followed by a letter, digit, or underscore
662: that is not to be interpreted as part of its name
663: or when a named parameter is subscripted.
664: If
665: .I parameter\^
666: is a digit then it is a positional parameter.
667: If
668: .I parameter\^
669: is
670: .BR \(**
671: or
672: .BR @ ,
673: then all the positional
674: parameters, starting with
675: .BR $1 ,
676: are substituted
677: (separated by spaces).
678: If an array
679: .I identifier\^
680: with subscript
681: .B \(**
682: or
683: .B @
684: is used,
685: then the value
686: for each of the
687: elements
688: is substituted
689: (separated by spaces).
690: .TP
691: \f3${#\fP\f2parameter\^\fP\f3}\fP
692: If
693: .I parameter\^
694: is not
695: .BR \(** ,
696: the length of the value of the
697: .I parameter\^
698: is substituted.
699: Otherwise, the number of positional parameters is substituted.
700: .TP
701: \f3${#\fP\f2identifier\fP\f3[*]}\fP
702: The number of elements in the array
703: .I identifier\^
704: is substituted.
705: .TP
706: \f3${\fP\f2parameter\^\fP\f3:\-\fP\f2word\^\fP\f3}\fP
707: If
708: .I parameter\^
709: is set and is non-null then substitute its value;
710: otherwise substitute
711: .IR word .
712: .TP
713: \f3${\fP\f2parameter\^\fP\f3:=\fP\f2word\^\fP\f3}\fP
714: If
715: .I parameter\^
716: is not set or is null then set it to
717: .IR word ;
718: the value of the parameter is then substituted.
719: Positional parameters may not be assigned to
720: in this way.
721: .TP
722: \f3${\fP\f2parameter\^\fP\f3:?\fP\f2word\^\fP\f3}\fP
723: If
724: .I parameter\^
725: is set and is non-null then substitute its value;
726: otherwise, print
727: .I word\^
728: and exit from the shell.
729: If
730: .I word\^
731: is omitted then a standard message is printed.
732: .TP
733: \f3${\fP\f2parameter\^\fP\f3:+\fP\f2word\^\fP\f3}\fP
734: If
735: .I parameter\^
736: is set and is non-null then substitute
737: .IR word ;
738: otherwise substitute nothing.
739: .TP
740: .PD 0
741: \f3${\fP\f2parameter\^\fP\f3#\fP\f2pattern\^\fP\f3}\fP
742: .TP
743: \f3${\fP\f2parameter\^\fP\f3##\fP\f2pattern\^\fP\f3}\fP
744: .PD
745: If
746: the Shell
747: .I pattern\^
748: matches the beginning of the value of
749: .IR parameter ,
750: then the value of
751: this substitution is the value of the
752: .I parameter\^
753: with the matched portion deleted;
754: otherwise the value of this
755: .I parameter\^
756: is substituted.
757: In the first form the smallest matching pattern is deleted and in the
758: latter form the largest matching pattern is deleted.
759: .TP
760: .PD 0
761: \f3${\fP\f2parameter\^\fP\f3%\fP\f2pattern\^\fP\f3}\fP
762: .TP
763: \f3${\fP\f2parameter\^\fP\f3%%\fP\f2pattern\^\fP\f3}\fP
764: .PD
765: If
766: the Shell
767: .I pattern\^
768: matches the end of the value of
769: .IR parameter ,
770: then the value of
771: .I parameter\^
772: with the matched part deleted;
773: otherwise substitute the value of
774: .IR parameter .
775: In the first form the smallest matching pattern is deleted and in the
776: latter form the largest matching pattern is deleted.
777: .PD
778: .PP
779: In the above,
780: .I word\^
781: is not evaluated unless it is
782: to be used as the substituted string,
783: so that, in the following example,
784: .B pwd\^
785: is executed only if
786: .B d\^
787: is not set or is null:
788: .RS
789: .PP
790: echo \|${d:\-\^\*`\^pwd\^\*`\^}
791: .RE
792: .PP
793: If the colon (
794: .B : )
795: is omitted from the above expressions,
796: then the shell only checks whether
797: .I parameter\^
798: is set or not.
799: .PP
800: The following
801: parameters
802: are automatically set by the shell:
803: .RS
804: .PD 0
805: .TP
806: .B #
807: The number of positional parameters in decimal.
808: .TP
809: .B \-
810: Flags supplied to the shell on invocation or by
811: the
812: .B set
813: command.
814: .TP
815: .B ?
816: The decimal value returned by the last executed command.
817: .TP
818: .B $
819: The process number of this shell.
820: .TP
821: .B _
822: The last argument of the previous command.
823: This parameter is not set for commands which are asynchronous.
824: .TP
825: .B !
826: The process number of the last background command invoked.
827: .TP
828: .B
829: .SM PPID
830: The process number of the parent of the shell.
831: .TP
832: .B
833: .SM PWD
834: The present working directory set by the
835: .B cd
836: command.
837: .TP
838: .B
839: .SM OLDPWD
840: The previous working directory set by the
841: .B cd
842: command.
843: .TP
844: .B
845: .SM RANDOM
846: Each time this parameter is referenced, a random integer is generated.
847: The sequence of random numbers can be initialized by assigning
848: a numeric value to
849: .SM
850: .BR RANDOM .
851: .TP
852: .B
853: .SM REPLY
854: This parameter is set by the
855: .B select
856: statement and by
857: the
858: .B read
859: special command when no arguments are supplied.
860: .PD
861: .RE
862: .PP
863: The following
864: parameters
865: are used by the shell:
866: .RS
867: .PD 0
868: .TP
869: .B
870: .SM CDPATH
871: The search path for the
872: .I cd
873: command.
874: .TP
875: .B
876: .SM COLUMNS
877: If this variable is set,
878: the value is used to define the width of the edit window
879: for the shell edit modes and for printing
880: .B select
881: lists.
882: .TP
883: .B
884: .SM EDITOR
885: If the value of this variable ends in
886: .IR emacs ,
887: .IR gmacs ,
888: or
889: .I vi
890: and the
891: .B
892: .SM VISUAL
893: variable is not set,
894: then the corresponding option
895: (see Special Command
896: .B set
897: below)
898: will be turned on.
899: .TP
900: .SM
901: .B ENV
902: If this parameter is set, then
903: parameter substitution is performed on
904: the value to generate
905: the pathname of the script that will be
906: executed when the
907: .I shell\^
908: is invoked.
909: (See
910: .I Invocation\^
911: below.)
912: This file is typically used for
913: .I alias
914: and
915: .I function
916: definitions.
917: .TP
918: .B
919: .SM FCEDIT
920: The default editor name for the
921: .B fc
922: command.
923: .TP
924: .SM
925: .B IFS
926: Internal field separators,
927: normally
928: .BR space ,
929: .BR tab ,
930: and
931: .B new-line
932: that is used to separate command words which result from
933: command or parameter substitution
934: and for separating words with the special command
935: .BR read .
936: .TP
937: .SM
938: .B HISTFILE
939: If this parameter is set when the shell is invoked, then
940: the value is the pathname of the file that will be
941: used to store the command history.
942: (See
943: .I "Command re-entry\^"
944: below.)
945: .TP
946: .SM
947: .B HISTSIZE
948: If this parameter is set when the shell is invoked, then
949: the number of previously entered commands that
950: are accessible by this shell
951: will be greater than or equal to this number.
952: The default is 128.
953: .TP
954: .B
955: .SM HOME
956: The default argument (home directory) for the
957: .B cd
958: command.
959: .TP
960: .B
961: .SM MAIL
962: If this parameter is set to the name of a mail file
963: .I and\^
964: the
965: .B
966: .SM MAILPATH
967: parameter is not set,
968: then the shell informs the user of arrival of mail
969: in the specified file.
970: .TP
971: .B
972: .SM MAILCHECK
973: This variable specifies how often (in seconds) the
974: shell will check for changes in the modification time
975: of any of the files specified by the
976: .B
977: .SM MAILPATH
978: or
979: .B
980: .SM MAIL
981: parameters.
982: The default value is 600 seconds.
983: If set to 0,
984: the shell will check before each prompt.
985: .TP
986: .B
987: .SM MAILPATH
988: A colon (
989: .B :
990: )
991: separated list of file names.
992: If this parameter is set
993: then the shell informs the user of
994: any modifications to the specified files
995: that have occurred within the last
996: .B
997: .SM MAILCHECK
998: seconds.
999: Each file name can be followed by a
1000: .B ?
1001: and a message that will be printed.
1002: The message will undergo parameter and command substitution
1003: with the parameter,
1004: .B $_
1005: defined as the name of the file that has changed.
1006: The default message is
1007: .I you have mail in $_\^.
1008: .TP
1009: .B
1010: .SM PATH
1011: The search path for commands (see
1012: .I Execution\^
1013: below).
1014: The user may not change
1015: .B \s-1PATH\s+1
1016: if executing under
1017: .I rsh
1018: (except in
1019: .I .profile\^
1020: ).
1021: .TP
1022: .SM
1023: .B PS1
1024: The value of this parameter is expanded for paramter
1025: substitution to define the
1026: primary prompt string which by default is
1027: .RB `` "$ \|" ''.
1028: The character
1029: .B !
1030: in the primary prompt string is replaced by the
1031: .I command\^
1032: number (see
1033: .I Command Re-entry
1034: below).
1035: .TP
1036: .SM
1037: .B PS2
1038: Secondary prompt string, by default
1039: .RB `` "> \|" ''.
1040: .TP
1041: .SM
1042: .B PS3
1043: Selection prompt string
1044: used within a
1045: .B select
1046: loop, by default
1047: .RB `` "#? \|" ''.
1048: .TP
1049: .SM
1050: .B SHELL
1051: The pathname of the
1052: .I shell\^
1053: is kept in the environment.
1054: At invocation, if the value of this variable contains an
1055: .B r
1056: in the basename,
1057: then the shell becomes restricted.
1058: .TP
1059: .B
1060: .SM TMOUT
1061: If set to a value greater than zero,
1062: the shell will terminate if a command is not entered within
1063: the prescribed number of seconds.
1064: (Note that the shell can be compiled with a maximum bound
1065: for this value which cannot be exceeded.)
1066: .TP
1067: .B
1068: .SM VISUAL
1069: If the value of this variable ends in
1070: .IR emacs ,
1071: .IR gmacs ,
1072: or
1073: .I vi
1074: then the corresponding option
1075: (see Special Command
1076: .B set
1077: below)
1078: will be turned on.
1079: .PD
1080: .RE
1081: .PP
1082: The shell gives default values to
1083: \f3\s-1PATH\s+1\fP, \f3\s-1PS1\s+1\fP, \f3\s-1PS2\s+1\fP, \f3\s-1MAILCHECK\s+1\fP,
1084: \f3\s-1TMOUT\s+1\fP and \f3\s-1IFS\s+1\fP,
1085: while
1086: .SM
1087: .BR HOME ,
1088: .SM
1089: .B SHELL
1090: .SM
1091: .B ENV
1092: and
1093: .SM
1094: .B MAIL
1095: are
1096: not set at all by the shell (although
1097: .SM
1098: .B HOME
1099: .I is\^
1100: set by
1101: .IR login (1)).
1102: On some systems
1103: .SM
1104: .B MAIL
1105: and
1106: .SM
1107: .B SHELL
1108: are also
1109: set by
1110: .IR login (1)).
1111: .SS Blank Interpretation.
1112: After parameter and command substitution,
1113: the results of substitutions are scanned for the field separator
1114: characters (
1115: those found in
1116: .SM
1117: .B IFS
1118: )
1119: and split into distinct arguments where such characters are found.
1120: Explicit null arguments (\^\f3"\^"\fP or \f3\*\(fm\^\*\(fm\fP\^) are retained.
1121: Implicit null arguments
1122: (those resulting from
1123: .I parameters\^
1124: that have no values) are removed.
1125: .SS File Name Generation.
1126: Following substitution, each command
1127: .I word\^
1128: is scanned for
1129: the characters
1130: .BR \(** ,
1131: .BR ? ,
1132: and
1133: .B \*(OK\^
1134: unless the
1135: .B \-f
1136: option has been
1137: .BR set .
1138: If one of these characters appears
1139: then the word is regarded as a
1140: .IR pattern .
1141: The word is replaced with alphabetically sorted file names that match the pattern.
1142: If no file name is found that matches the pattern, then
1143: the word is left unchanged.
1144: When a
1145: .I pattern\^
1146: is used for file name generation,
1147: the character
1148: .B .
1149: at the start of a file name
1150: or immediately following a
1151: .BR / ,
1152: as well as the character
1153: .B /
1154: itself,
1155: must be matched explicitly.
1156: In other instances of pattern matching the
1157: .B /
1158: and
1159: .B .
1160: are not treated specially.
1161: .PP
1162: .PD 0
1163: .RS
1164: .TP
1165: .B \(**
1166: Matches any string, including the null string.
1167: .TP
1168: .B ?
1169: Matches any single character.
1170: .TP
1171: .BR \*(OK \^.\|.\|.\^ \*(CK
1172: Matches any one of the enclosed characters.
1173: A pair of characters separated by
1174: .B \-
1175: matches any
1176: character lexically between the pair, inclusive.
1177: If the first character following the opening "[ \|"
1178: is a "! \|" then any character not enclosed is matched.
1179: A
1180: .B \-
1181: can be included in the character set by putting it as the
1182: first or last character.
1183: .PD
1184: .RE
1185: .SS Quoting.
1186: Each of the
1187: .I metacharacters\^
1188: listed above (See
1189: .I Definitions
1190: above).
1191: has a special meaning to the shell
1192: and cause termination of a word unless quoted.
1193: A character may be
1194: .I quoted\^
1195: (i.e., made to stand for itself)
1196: by preceding
1197: it with a
1198: .BR \e .
1199: The pair
1200: .B \enew-line
1201: is ignored.
1202: All characters enclosed between a pair of single quote marks (\^\f3\(fm\^\(fm\fP\^),
1203: except a single quote,
1204: are quoted.
1205: Inside double quote marks
1206: (\f3"\^"\fP),
1207: parameter and command substitution occurs and
1208: .B \e
1209: quotes the characters
1210: .BR \e ,
1211: .BR \(fm ,
1212: \f3"\fP,
1213: and
1214: .BR $ .
1215: .B
1216: "$\(**"
1217: is equivalent to
1218: \f3"$1 \|$2\fP \|.\|.\|.\f3"\fP,
1219: whereas
1220: .B
1221: "$@"
1222: is equivalent to
1223: .B
1224: "$1"\|
1225: .B
1226: "$2"\|
1227: \&.\|.\|.\^.
1228: .PP
1229: The special meaning of keywords can be removed by quoting any
1230: character of the keyword.
1231: The recognition of special command names listed below cannot be altered
1232: by quoting them.
1233: .SS Arithmetic Evaluation.
1234: An ability to perform integer arithmetic
1235: is provided with the special command
1236: .BR let .
1237: Evaluations are performed using
1238: .I long\^
1239: arithmetic.
1240: Constants are of the form
1241: \*(OK\f2base\f3#\^\f1\*(CK\f2n\^\fP
1242: where
1243: .I base\^
1244: is a decimal number between two and thirty-six
1245: representing the arithmetic base
1246: and
1247: .I n\^
1248: is a number in that base.
1249: If
1250: .I base\^
1251: is omitted
1252: then base 10 is used.
1253: .PP
1254: An internal integer representation of a
1255: .I named parameter\^
1256: can be specified with the
1257: .B \-i
1258: option of the
1259: .B typeset
1260: special command.
1261: When this attribute is selected
1262: the first assignment to the
1263: parameter determines the arithmetic base
1264: to be used when
1265: parameter substitution occurs.
1266: .PP
1267: Since many of the arithmetic operators require
1268: quoting, an alternative form of the
1269: .B let
1270: command is provided.
1271: For any command which begins with a
1272: .BR (( ,
1273: all the characters until a matching
1274: .B ))
1275: are treated as a quoted expression.
1276: More precisely,
1277: .B ((
1278: \&.\|.\|.
1279: .B ))
1280: is equivalent to
1281: .B let\^
1282: \f3"\fP \|.\|.\|.\f3"\fP.
1283: .SS Prompting.
1284: When used interactively,
1285: the shell prompts with the value of
1286: .SM
1287: .B PS1
1288: before reading a command.
1289: If at any time a new-line is typed and further input is needed
1290: to complete a command, then the secondary prompt
1291: (i.e., the value of
1292: .BR \s-1PS2\s+1 )
1293: is issued.
1294: .SS Input/Output.
1295: Before a command is executed, its input and output
1296: may be redirected using a special notation interpreted by the shell.
1297: The following may appear anywhere in a simple-command
1298: or may precede or follow a
1299: .I command\^
1300: and are
1301: .I not\^
1302: passed on to the invoked command.
1303: Command and parameter substitution occurs before
1304: .I word\^
1305: or
1306: .I digit\^
1307: is used except as noted below.
1308: File name generation
1309: occurs only if the pattern matches a single file
1310: and blank interpretation is not performed.
1311: .TP 14
1312: .BI < word
1313: Use file
1314: .I word\^
1315: as standard input (file descriptor 0).
1316: .TP
1317: .BI > word
1318: Use file
1319: .I word\^
1320: as standard output (file descriptor 1).
1321: If the file does not exist then it is created;
1322: otherwise, it is truncated to zero length.
1323: .TP
1324: .BI >\[email protected]@> word
1325: Use file
1326: .I word\^
1327: as standard output.
1328: If the file exists then output is appended to it (by first seeking to the end-of-file);
1329: otherwise, the file is created.
1330: .TP
1331: \f3<\[email protected]@<\fP\*(OK\f3\-\fP\*(CK\f2word\fP
1332: The shell input is read up to a line that is the same as
1333: .IR word ,
1334: or to an end-of-file.
1335: No parameter substitution, command substitution or
1336: file name generation is performed on
1337: .IR word .
1338: The resulting document,
1339: called a
1340: .IR here-document ,
1341: becomes
1342: the standard input.
1343: If any character of
1344: .I word\^
1345: is quoted, then no interpretation
1346: is placed upon the characters of the document;
1347: otherwise, parameter and command substitution occurs,
1348: .B \enew-line
1349: is ignored,
1350: and
1351: .B \e
1352: must be used to quote the characters
1353: .BR \e ,
1354: .BR $ ,
1355: .BR \*` ,
1356: and the first character of
1357: .IR word .
1358: If
1359: .B \-
1360: is appended to
1361: .BR <\[email protected]@< ,
1362: then all leading tabs are stripped from
1363: .I word\^
1364: and from the document.
1365: .TP
1366: .BI <& digit
1367: The standard input is duplicated from file descriptor
1368: .I digit
1369: (see
1370: .IR dup (2)).
1371: Similarly for the standard output using
1372: .BR >&
1373: .IR digit .
1374: .TP
1375: .B <&\-
1376: The standard input is closed.
1377: Similarly for the standard output using
1378: .BR >&\- .
1379: .PP
1380: If one of the above is preceded by a digit,
1381: then the
1382: file descriptor number referred to is that specified
1383: by the digit
1384: (instead of the default 0 or 1).
1385: For example:
1386: .RS
1387: .PP
1388: \&.\|.\|. \|2>&1
1389: .RE
1390: .PP
1391: means file descriptor 2 is to be opened
1392: for writing as a duplicate
1393: of file descriptor 1.
1394: .PP
1395: The order in which redirections are specified is significant.
1396: The shell evaluates each redirection in terms of the
1397: .RI ( "file descriptor" ", " file )
1398: association at the time of evaluation.
1399: For example:
1400: .RS
1401: .PP
1402: \&.\|.\|. \|1>\f2fname\^\fP 2>&1
1403: .RE
1404: .PP
1405: first associates file descriptor 1 with file
1406: .IR fname\^ .
1407: It then associates file descriptor 2 with the file associated with file
1408: descriptor 1 (i.e.
1409: .IR fname\^ ).
1410: If the order of redirections were reversed, file descriptor 2 would be associated
1411: with the terminal (assuming file descriptor 1 had been) and then file descriptor
1412: 1 would be associated with file
1413: .IR fname\^ .
1414: .PP
1415: If a command is followed by
1416: .B &
1417: and job control is not active,
1418: then the default standard input
1419: for the command
1420: is the empty file
1421: .BR /dev/null .
1422: Otherwise, the environment for the execution of a command contains the
1423: file descriptors of the invoking shell as modified by
1424: input/output specifications.
1425: .SS Environment.
1426: The
1427: .I environment\^
1428: (see
1429: .IR environ (7))
1430: is a list of name-value pairs that is passed to
1431: an executed program in the same way as a normal argument list.
1432: The names must be
1433: .I identifiers\^
1434: and the values are character strings.
1435: The shell interacts with the environment in several ways.
1436: On invocation, the shell scans the environment
1437: and creates a
1438: parameter
1439: for each name found,
1440: giving it the corresponding value and marking it
1441: .I export .
1442: Executed commands inherit the environment.
1443: If the user modifies the values of these
1444: parameters
1445: or creates new ones,
1446: using the
1447: .B export
1448: or
1449: .B typeset \-x
1450: commands they become part of the
1451: environment.
1452: The environment seen by any executed command is thus composed
1453: of any name-value pairs originally inherited by the shell,
1454: whose values may be modified by the current shell,
1455: plus any additions
1456: which must be noted in
1457: .B export
1458: or
1459: .B typeset \-x
1460: commands.
1461: .PP
1462: The environment for any
1463: .I simple-command\^
1464: or function
1465: may be augmented by prefixing it with one or more parameter assignments.
1466: A parameter assignment argument is a word of the form
1467: .IR identifier=value .
1468: Thus:
1469: .RS
1470: .PP
1471: \s-1TERM\s+1=450 \|cmd \|args and
1472: .br
1473: (export \|\s-1TERM\s+1; \|\s-1TERM\s+1=450; \|cmd \|args)
1474: .RE
1475: .PP
1476: are equivalent (as far as the above execution of
1477: .I cmd\^
1478: is concerned).
1479: .PP
1480: If the
1481: .B \-k
1482: flag is set,
1483: .I all\^
1484: parameter assignment arguments are placed in the environment,
1485: even if they occur after the command name.
1486: The following
1487: first prints
1488: .B "a=b c"
1489: and then
1490: .BR c:
1491: .PP
1492: .RS
1493: .nf
1494: echo \|a=b \|c
1495: set \|\-k
1496: echo \|a=b \|c
1497: .fi
1498: .RE
1499: .SS Functions.
1500: .PP
1501: The
1502: .B function\^
1503: keyword, described in the
1504: .I Commands
1505: section above,
1506: is used to define shell functions.
1507: Shell functions are read in and stored internally.
1508: Alias names are resolved when the function is read.
1509: Functions are executed like commands with the arguments
1510: passed as positional parameters.
1511: (See
1512: .I Execution
1513: below).
1514: .PP
1515: Functions execute in the same process as the caller and
1516: share all files, traps ( other than
1517: .SM
1518: .B EXIT
1519: and
1520: .SM
1521: .BR ERR )
1522: and present working directory with the
1523: caller.
1524: A trap set on
1525: .SM
1526: .B EXIT
1527: inside a function
1528: is executed after the function completes.
1529: Ordinarily,
1530: variables are shared between the calling program
1531: and the function.
1532: However,
1533: the
1534: .B typeset
1535: special command used within a function
1536: defines local variables whose scope includes
1537: the current function and
1538: all functions it calls.
1539: .PP
1540: The special command
1541: .B return
1542: is used to return
1543: from function calls.
1544: Errors within functions return control to the caller.
1545: .PP
1546: Function identifiers
1547: can be listed with the
1548: .B \-f
1549: option of the
1550: .B typeset
1551: special command.
1552: The text of functions will also
1553: be listed.
1554: Function can be undefined with the
1555: .B \-f
1556: option of the
1557: .B unset
1558: special command.
1559: .PP
1560: Ordinarily,
1561: functions are unset when the shell executes a shell script.
1562: The
1563: .B \-xf
1564: option of the
1565: .B typeset
1566: command allows a function to be exported
1567: to scripts that are executed without a separate
1568: invocation of the shell.
1569: Functions that need to be defined across separate
1570: invocations of the shell should be placed in the
1571: .B
1572: .SM
1573: ENV
1574: file.
1575: .SS Jobs.
1576: .PP
1577: If the
1578: .B monitor
1579: option of the
1580: .B set
1581: command is turned on,
1582: an interactive shell associates a \fIjob\fR with each pipeline. It keeps
1583: a table of current jobs, printed by the
1584: .B jobs
1585: command, and assigns them small integer numbers. When
1586: a job is started asynchronously with
1587: .BR & ,
1588: the shell prints a line which looks
1589: like:
1590: .PP
1591: .DT
1592: [1] 1234
1593: .PP
1594: indicating that the job which was started asynchronously was job number
1595: 1 and had one (top-level) process, whose process id was 1234.
1596: .PP
1597: This paragraph and the next require features that are
1598: not in all versions of UNIX and may not apply.
1599: If you are running a job and wish to do something else you may hit the key
1600: \fB^Z\fR (control-Z) which sends a STOP signal to the current job.
1601: The shell will then normally indicate that the job has been `Stopped',
1602: and print another prompt. You can then manipulate the state of this job,
1603: putting it in the background with the
1604: .B bg
1605: command, or run some other
1606: commands and then eventually bring the job back into the foreground with
1607: the foreground command
1608: .BR fg .
1609: A \fB^Z\fR takes effect immediately and
1610: is like an interrupt in that pending output and unread input are discarded
1611: when it is typed.
1612: .PP
1613: A job being run in the background will stop if it tries to read
1614: from the terminal. Background jobs are normally allowed to produce output,
1615: but this can be disabled by giving the command ``stty tostop''.
1616: If you set this
1617: tty option, then background jobs will stop when they try to produce
1618: output like they do when they try to read input.
1619: .PP
1620: There are several ways to refer to jobs in the shell. The character
1621: .B %
1622: introduces a job name. If you wish to refer to job number 1, you can
1623: name it as
1624: .B %1 .
1625: Jobs can also be named by prefixes of the string typed in to
1626: .B kill
1627: or restart them.
1628: Thus, on systems that support job control,
1629: .RB ` fg
1630: .BR %ed '
1631: would normally restart
1632: a suspended
1633: .IR ed (1)
1634: job, if there were a suspended job whose name began with
1635: the string `ed'.
1636: .PP
1637: The shell maintains a notion of the current and previous jobs.
1638: In output pertaining to jobs, the current job is marked with a
1639: .B +
1640: and the previous job with a
1641: .BR \- .
1642: The abbreviation
1643: .B %+
1644: refers
1645: to the current job and
1646: .B %\-
1647: refers to the previous job.
1648: .B %%
1649: is also a synonym for the current job.
1650: .PP
1651: This shell learns immediately whenever a process changes state.
1652: It normally informs you whenever a job becomes blocked so that
1653: no further progress is possible, but only just before it prints
1654: a prompt. This is done so that it does not otherwise disturb your work.
1655: .PP
1656: When you try to leave the shell while jobs are running or stopped, you will
1657: be warned that `You have stopped(running) jobs.' You may use the
1658: .B jobs
1659: command to see what they are. If you do this or immediately try to
1660: exit again, the shell will not warn you a second time, and the stopped
1661: jobs will be terminated.
1662: .SS Signals.
1663: The \s-1INT\s+1 and \s-1QUIT\s+1 signals for an invoked
1664: command are ignored if the command is followed by
1665: .B &
1666: and job
1667: .B monitor
1668: option is not active.
1669: Otherwise, signals have the values
1670: inherited by the shell from its parent,
1671: with the exception of signal 11
1672: (but see also
1673: the
1674: .B trap
1675: command below).
1676: .SS Execution.
1677: Each time a command is executed, the above substitutions
1678: are carried out.
1679: If the command name matches one
1680: of the
1681: .I "Special Commands\^"
1682: listed below,
1683: it is executed within the
1684: current shell process.
1685: Next, the command name is checked to see if
1686: it matches one of the user defined functions.
1687: If it does,
1688: the positional parameters are saved
1689: and then reset to the arguments of the
1690: .I function\^
1691: call.
1692: When the
1693: .I function\^
1694: completes or issues a
1695: .BR return ,
1696: the positional parameter list is restored
1697: and any trap set on
1698: .SM
1699: .B EXIT
1700: within the function is executed.
1701: The value of a
1702: .I function\^
1703: is the value of the last command executed.
1704: A function is also executed in the
1705: current shell process.
1706: If a command name is not a
1707: .I "special command\^"
1708: or a user defined
1709: .IR function ,
1710: a process is created and
1711: an attempt is made to execute the command via
1712: .IR exec (2).
1713: .PP
1714: The shell parameter
1715: .B
1716: .SM PATH
1717: defines the search path for
1718: the directory containing the command.
1719: Alternative directory names are separated by
1720: a colon
1721: .RB ( : ).
1722: The default path is
1723: .B :/bin:/usr/bin
1724: (specifying the current directory,
1725: .BR /bin ,
1726: and
1727: .BR /usr/bin ,
1728: in that order).
1729: Note that the current directory
1730: is specified by a null path name,
1731: which can appear immediately after the
1732: equal sign, between colon delimiters,
1733: or at the end of the path list.
1734: If the command name contains a \f3/\fP then the search path
1735: is not used.
1736: Otherwise, each directory in the path is
1737: searched for an executable file.
1738: If the file has execute permission but is not a
1739: directory or an
1740: .B a.out
1741: file,
1742: it is assumed to be a file containing shell commands.
1743: A sub-shell is spawned to read it.
1744: All non-exported aliases,
1745: functions,
1746: and named parameters are removed in this case.
1747: A parenthesized command is also executed in
1748: a sub-shell.
1749: .SS Command Re-entry.
1750: The text of the last
1751: .B
1752: .SM
1753: HISTSIZE
1754: (default 128)
1755: commands entered from a terminal device
1756: is saved in a
1757: .I history
1758: file.
1759: The file
1760: .B \s-1$HOME\s+1/.history
1761: is used if the
1762: .B
1763: .SM
1764: HISTFILE
1765: variable is not set
1766: or is not writable.
1767: A shell can access the commands of
1768: all
1769: .I interactive
1770: shells which use the same named
1771: .SM
1772: .BR HISTFILE .
1773: The special command
1774: .B fc\^
1775: is used to list or
1776: edit a portion this file.
1777: The portion of the file to be edited or listed can be selected by
1778: number or by giving the first character or
1779: characters of the command.
1780: A single command or range of commands can be specified.
1781: If you do not specify an editor program as
1782: an argument to
1783: .B fc\^
1784: then the value of the parameter
1785: .SM
1786: .B FCEDIT
1787: is used.
1788: If
1789: .SM
1790: .B FCEDIT
1791: is not defined then
1792: .I /bin/ed
1793: is used.
1794: The edited command(s) is printed and re-executed upon
1795: leaving the editor.
1796: The editor name
1797: .B \-
1798: is used to skip the editing phase and
1799: to re-execute the command.
1800: In this case a substitution parameter of the form
1801: \f2old\fP\f3=\fP\f2new\fP
1802: can be used to modify the command before execution.
1803: For example, if
1804: .B r
1805: is aliased to
1806: .B \(fmfc \-e \-\(fm
1807: then typing
1808: `\f3r bad=good c\fP'
1809: will re-execute the most recent command which starts with the letter
1810: .BR c ,
1811: replacing the string
1812: .B bad
1813: with the string
1814: .BR good .
1815: .SS In-line Editing Options
1816: Normally, each command line entered from a terminal device is simply
1817: typed followed by a new-line (`RETURN' or `LINE\ FEED').
1818: If either the
1819: .IR emacs ,
1820: .IR gmacs ,
1821: or
1822: .I vi
1823: option is active, the user can edit the command line.
1824: To be in either of these edit modes
1825: .B set
1826: the corresponding
1827: option.
1828: An editing option is automatically selected each time the
1829: .SM
1830: .B VISUAL
1831: or
1832: .SM
1833: .B EDITOR
1834: variable is assigned a value ending in either of these
1835: option names.
1836: .PP
1837: The editing features require that the user's terminal
1838: accept `RETURN' as carriage return without line feed
1839: and that a space (`\ ' must overwrite the current character on
1840: the screen.
1841: ADM terminal users should set the "space\ -\ advance"
1842: switch to `space'.
1843: Hewlett-Packard series 2621 terminal users should set the straps to
1844: `bcGHxZ\ etX'.
1845: .PP
1846: The editing modes implement a concept where the user is looking through a
1847: window at the current line.
1848: The window width is the value of
1849: .SM
1850: .B COLUMNS
1851: if it is defined, otherwise 80.
1852: If the line is longer than the window width minus two, a mark is
1853: displayed at the end of the window to notify the user.
1854: As the cursor moves and reaches the window boundaries the window will be
1855: centered about the cursor.
1856: The mark is a
1857: .BR > " ("
1858: .BR < ", "
1859: .BR * )
1860: if the line extends on the
1861: right (left, both) side(s) of the window.
1862: .SS Emacs Editing Mode
1863: This mode is entered by enabling either the
1864: .I emacs
1865: or
1866: .I gmacs
1867: option.
1868: The only difference between these two modes is the way
1869: they handle
1870: .BR ^T .
1871: To edit, the user
1872: moves the cursor to the point needing correction and
1873: then inserts or deletes characters or words as needed.
1874: All the editing commands are control characters or escape
1875: sequences.
1876: The notation for control characters is caret (
1877: .B ^
1878: ) followed
1879: by the character.
1880: For example,
1881: .B ^F
1882: is the notation for control
1883: .BR F .
1884: This is entered by depressing `f' while holding down the
1885: `CTRL' (control) key.
1886: The `SHIFT' key is
1887: .I not
1888: depressed.
1889: (The notation
1890: .B ^?
1891: indicates the DEL (delete) key.)
1892: .PP
1893: The notation for escape sequences is
1894: .B M-
1895: followed by a
1896: character.
1897: For example,
1898: .B M-f
1899: (pronounced Meta f)
1900: is entered by depressing ESC
1901: (ascii
1902: .B 033
1903: )
1904: followed by `f'.
1905: (
1906: .B M-F
1907: would be the notation for ESC followed by `SHIFT' (capital) `F'.)
1908: .PP
1909: All edit commands
1910: operate from any place on the line
1911: (not just at the beginning).
1912: Neither the "RETURN" nor the "LINE FEED" key is
1913: entered after edit commands except when noted.
1914: .PP
1915: .PD 0
1916: .TP 10
1917: .BI ^F
1918: Move cursor forward (right) one character.
1919: .PP
1920: .TP 10
1921: .BI M-f
1922: Move cursor forward one word.
1923: (The editor's idea of a word is a string of characters
1924: consisting of only letters, digits and underscores.)
1925: .PP
1926: .TP 10
1927: .BI ^B
1928: Move cursor backward (left) one character.
1929: .PP
1930: .TP 10
1931: .BI M-b
1932: Move cursor backward one word.
1933: .PP
1934: .TP 10
1935: .BI ^A
1936: Move cursor to start of line.
1937: .PP
1938: .TP 10
1939: .BI ^E
1940: Move cursor to end of line.
1941: .PP
1942: .TP 10
1943: .BI ^] char
1944: Move cursor to character
1945: .I char
1946: on current line.
1947: .PP
1948: .TP 10
1949: .BI ^X^X
1950: Interchange the cursor and mark.
1951: .PP
1952: .TP 10
1953: .I erase
1954: (User defined erase character as defined
1955: by the stty command, usually
1956: .B ^H
1957: or
1958: .BR # .)
1959: Delete previous character.
1960: .PP
1961: .TP 10
1962: .BI ^D
1963: Delete current character.
1964: .PP
1965: .TP 10
1966: .BI M-d
1967: Delete current word.
1968: .PP
1969: .TP 10
1970: .BI M-^H
1971: (Meta-backspace) Delete previous word.
1972: .PP
1973: .TP 10
1974: .BI M-h
1975: Delete previous word.
1976: .PP
1977: .TP 10
1978: .BI M-^?
1979: (Meta-DEL) Delete previous word (if your interrupt character is
1980: .B ^?
1981: (DEL, the default) then this command will not work).
1982: .PP
1983: .TP 10
1984: .BI ^T
1985: Transpose current character with next character in
1986: .I emacs
1987: mode.
1988: Transpose two previous characters in
1989: .I gmacs
1990: mode.
1991: .PP
1992: .TP 10
1993: .BI ^C
1994: Capitalize current character.
1995: .PP
1996: .TP 10
1997: .BI M-C
1998: Capitalize current word.
1999: .PP
2000: .TP 10
2001: .BI ^K
2002: Kill from the cursor to the end of the line.
2003: If given a parameter of zero then kill from
2004: the start of line to the cursor.
2005: .PP
2006: .TP 10
2007: .BI ^W
2008: Kill from the cursor to the mark.
2009: .PP
2010: .TP 10
2011: .BI M-p
2012: Push the region from the cursor to the mark on the stack.
2013: .PP
2014: .TP 10
2015: .I kill
2016: (User defined kill character as defined
2017: by the stty command, usually
2018: .B ^G
2019: or
2020: .BR @ .)
2021: Kill the entire current line.
2022: If two
2023: .I kill
2024: characters are entered in succession, all
2025: kill characters from then on cause a line feed
2026: (useful when using paper terminals).
2027: .PP
2028: .TP 10
2029: .BI ^Y
2030: Restore last item removed from line. (Yank item back to the line.)
2031: .PP
2032: .TP 10
2033: .BI ^L
2034: Line feed and print current line.
2035: .PP
2036: .TP 10
2037: .BI ^@
2038: (Null character) Set mark.
2039: .PP
2040: .TP 10
2041: .BI M-
2042: (Meta space) Set mark.
2043: .PP
2044: .TP 10
2045: .BI ^J
2046: (New\ line) Execute the current line.
2047: .PP
2048: .TP 10
2049: .BI ^M
2050: (Return) Execute the current line.
2051: .PP
2052: .TP 10
2053: .I eof
2054: End-of-file character,
2055: normally
2056: .BR ^D ,
2057: will terminate the shell
2058: if the current line is null.
2059: .PP
2060: .TP 10
2061: .BI ^P
2062: Fetch previous command.
2063: Each time
2064: .B ^P
2065: is entered
2066: the previous command back in time is accessed.
2067: .PP
2068: .TP 10
2069: .BI M-<
2070: Fetch the least recent (oldest) history line.
2071: .PP
2072: .TP 10
2073: .BI M->
2074: Fetch the most recent (youngest) history line.
2075: .PP
2076: .TP 10
2077: .BI ^N
2078: Fetch next command.
2079: Each time
2080: .B ^N
2081: is entered
2082: the next command forward in time is accessed.
2083: .PP
2084: .TP 10
2085: .BI ^R string
2086: Reverse search history for a previous command line containing
2087: .IR string .
2088: If a parameter of zero is given the search is forward.
2089: .I String
2090: is terminated by a "RETURN" or "NEW\ LINE".
2091: .PP
2092: .TP 10
2093: .B ^O
2094: Operate \- Execute the current line and fetch
2095: the next line relative to current line from the
2096: history file.
2097: .PP
2098: .TP 10
2099: .BI M- digits
2100: (Escape) Define numeric parameter, the digits
2101: are taken as a parameter to the next command.
2102: The commands that accept a parameter are
2103: .BR ^F ,
2104: .BR ^B ,
2105: .IR erase ,
2106: .BR ^D ,
2107: .BR ^K ,
2108: .BR ^R ,
2109: .B ^P
2110: and
2111: .BR ^N .
2112: .PP
2113: .TP 10
2114: .BI M- letter
2115: Soft-key \- Your alias list is searched for an
2116: alias by the name
2117: .BI _ letter
2118: and if an alias of this name is defined, its
2119: value will be inserted on the line.
2120: The
2121: .I letter
2122: must not be one of the above meta-functions.
2123: .PP
2124: .TP 10
2125: .B M-_
2126: The last parameter of the previous command is inserted
2127: on the line.
2128: .PP
2129: .TP 10
2130: .B M-.
2131: The last parameter of the previous command is inserted
2132: on the line.
2133: .PP
2134: .TP 10
2135: .B M-*
2136: Attempt file name generation on the current word.
2137: .PP
2138: .TP 10
2139: .BI ^U
2140: Multiply parameter of next command by 4.
2141: .PP
2142: .TP 10
2143: .BI \e
2144: Escape next character.
2145: Editing characters, the user's erase, kill and
2146: interrupt (normally
2147: .B ^?
2148: )
2149: characters
2150: may be entered
2151: in a command line or in a search string if preceded by a
2152: .BR \e .
2153: The
2154: .B \e
2155: removes the next character's
2156: editing features (if any).
2157: .PP
2158: .TP 10
2159: .BI ^V
2160: Display version of the shell.
2161: .PD
2162: .SS Vi Editing Mode
2163: There are two typing modes.
2164: Initially, when you enter a command you are in the
2165: .I input\^
2166: mode.
2167: To edit, the user enters
2168: .I control\^
2169: mode by typing ESC (
2170: .B 033
2171: ) and
2172: moves the cursor to the point needing correction and
2173: then inserts or deletes characters or words as needed.
2174: Most control commands accept an optional repeat
2175: .I count
2176: prior to the command.
2177: .P
2178: When in vi mode on most systems,
2179: canonical processing is initially enabled and the
2180: command will be echoed again if the speed is 1200 baud or greater and it
2181: contains any control characters or less than one second has elapsed
2182: since the prompt was printed.
2183: The ESC character terminates canonical processing for the remainder of the command
2184: and the user can than modify the command line.
2185: This scheme has the advantages of canonical processing with the type-ahead
2186: echoing of raw mode.
2187: .P
2188: If the option
2189: .B viraw\^
2190: is also set, the terminal will always have canonical processing
2191: disabled. This mode is implicit for systems that do not support two
2192: alternate end of line delimiters,
2193: and may be helpful for certain terminals.
2194: .SS "\ \ \ \ \ Input Edit Commands"
2195: .PP
2196: .RS
2197: By default the editor is in input mode.
2198: .PD 0
2199: .TP 10
2200: .I erase
2201: (User defined erase character as defined
2202: by the stty command, usually
2203: .B ^H
2204: or
2205: .BR # .)
2206: Delete previous character.
2207: .TP 10
2208: .BI ^W
2209: Delete the previous blank separated word.
2210: .TP 10
2211: .BI ^D
2212: Terminate the shell.
2213: .TP 10
2214: .BI ^V
2215: Escape next character.
2216: Editing characters, the user's erase or kill
2217: characters may be entered
2218: in a command line or in a search string if preceded by a
2219: .BR ^V .
2220: The
2221: .B ^V
2222: removes the next character's
2223: editing features (if any).
2224: .TP 10
2225: .BI \e
2226: Escape the next
2227: .I erase
2228: or
2229: .I kill
2230: character.
2231: .P
2232: .RE
2233: .SS "\ \ \ \ \ Motion Edit Commands"
2234: .RS
2235: These commands will move the cursor.
2236: .TP 10
2237: [\f2count\fP]\f3l\fP
2238: Cursor forward (right) one character.
2239: .TP 10
2240: [\f2count\fP]\f3w\fP
2241: Cursor forward one alpha-numeric word.
2242: .TP 10
2243: [\f2count\fP]\f3W\fP
2244: Cursor to the beginning of the next word that follows a blank.
2245: .TP 10
2246: [\f2count\fP]\f3e\fP
2247: Cursor to end of word.
2248: .TP 10
2249: [\f2count\fP]\f3E\fP
2250: Cursor to end of the current blank delimited word.
2251: .TP 10
2252: [\f2count\fP]\f3h\fP
2253: Cursor backward (left) one character.
2254: .TP 10
2255: [\f2count\fP]\f3b\fP
2256: Cursor backward one word.
2257: .TP 10
2258: [\f2count\fP]\f3B\fP
2259: Cursor to preceding blank separated word.
2260: .TP 10
2261: [\f2count\fP]\f3f\fP\f2c\fP
2262: Find the next character \fIc\fP in the current line.
2263: .TP 10
2264: [\f2count\fP]\f3F\fP\f2c\fP
2265: Find the previous character \fIc\fP in the current line.
2266: .TP 10
2267: [\f2count\fP]\f3t\fP\f2c\fP
2268: Equivalent to
2269: .B f
2270: followed by
2271: .BR h .
2272: .TP 10
2273: [\f2count\fP]\f3T\fP\f2c\fP
2274: Equivalent to
2275: .B F
2276: followed by
2277: .BR l .
2278: .TP 10
2279: .B ;
2280: Repeats the last single character find command,
2281: .BR f ,
2282: .BR F ,
2283: .BR t ,
2284: or
2285: .BR T .
2286: .TP 10
2287: .B ,
2288: Reverses the last single character find command.
2289: .TP 10
2290: .B 0
2291: Cursor to start of line.
2292: .TP 10
2293: .B ^
2294: Cursor to first non-blank character in line.
2295: .TP 10
2296: .B $
2297: Cursor to end of line.
2298: .RE
2299: .SS "\ \ \ \ \ Search Edit Commands"
2300: .RS
2301: These commands access your command history.
2302: .TP 10
2303: [\f2count\fP]\f3k\fP
2304: Fetch previous command.
2305: Each time
2306: .B k
2307: is entered
2308: the previous command back in time is accessed.
2309: .TP 10
2310: [\f2count\fP]\f3\-\fP
2311: Equivalent to
2312: .BR k .
2313: .TP 10
2314: [\f2count\fP]\f3j\fP
2315: Fetch next command.
2316: Each time
2317: .B j
2318: is entered
2319: the next command forward in time is accessed.
2320: .TP 10
2321: [\f2count\fP]\f3+\fP
2322: Equivalent to
2323: .BR j .
2324: .TP 10
2325: [\f2count\fP]\f3G\fP
2326: The command number
2327: .I count
2328: is fetched.
2329: The default is the least recent history command.
2330: .TP 10
2331: .BI / string
2332: Search backward through history for a previous command containing
2333: .IR string .
2334: .I String
2335: is terminated by a "RETURN" or "NEW\ LINE".
2336: If \fIstring\fP is null the previous string will be used.
2337: .TP 10
2338: .BI ? string
2339: Same as
2340: .B /
2341: except that search will be in the forward direction.
2342: .TP 10
2343: .B n
2344: Search for next match of the last pattern to
2345: .B /
2346: or
2347: .B ?
2348: commands.
2349: .TP 10
2350: .B N
2351: Search for next match of the last pattern to
2352: .B /
2353: or
2354: .BR ? ,
2355: but in reverse direction.
2356: Search history for the \fIstring\fP entered by the previous \fB/\fP command.
2357: .RE
2358: .SS "\ \ \ \ \ Text Modification Edit Commands"
2359: .RS
2360: These commands will modify the line.
2361: .TP 10
2362: .B a
2363: Enter input mode and enter text after the current character.
2364: .TP 10
2365: .B A
2366: Append text to the end of the line. Equivalent to
2367: .BR $a .
2368: .TP 10
2369: [\f2count\fP]\f3c\fP\f2motion\fP
2370: .TP 10
2371: \f3c\fP[\f2count\fP]\f2motion\fP
2372: Delete current character through the character
2373: .I motion
2374: moves the cursor to and enter input mode.
2375: If \fImotion\fP is
2376: .BR c ,
2377: the entire line will be deleted and
2378: input mode entered.
2379: .TP 10
2380: .B C
2381: Delete the current character through the end of line and enter input mode.
2382: Equivalent to
2383: .BR c$ .
2384: .TP 10
2385: .B S
2386: Equivalent to
2387: .BR cc .
2388: .TP 10
2389: .B D
2390: Delete the current character through the end of line.
2391: .TP 10
2392: [\f2count\fP]\f3d\fP\f2motion\fP
2393: .TP 10
2394: \f3d\fP[\f2count\fP]\f2motion\fP
2395: Delete current character through the character
2396: .I motion
2397: moves the cursor to. Equivalent to
2398: .BR d$ .
2399: If \fImotion\fP is
2400: .B d ,
2401: the entire line will be deleted.
2402: .TP 10
2403: .B i
2404: Enter input mode and insert text before the current character.
2405: .TP 10
2406: .B I
2407: Insert text before the beginning of the line. Equivalent to
2408: the two character sequence
2409: .BR ^i .
2410: .TP 10
2411: [\f2count\fP]\f3P\fP
2412: Place the previous text modification before the cursor.
2413: .TP 10
2414: [\f2count\fP]\f3p\fP
2415: Place the previous text modification after the cursor.
2416: .TP 10
2417: .B R
2418: Enter input mode and
2419: replace characters on the screen with characters you type overlay fashion.
2420: .TP 10
2421: .BI r c
2422: Replace the current character with
2423: .IR c .
2424: .TP 10
2425: [\f2count\fP]\f3x\fP
2426: Delete current character.
2427: .TP 10
2428: [\f2count\fP]\f3X\fP
2429: Delete preceding character.
2430: .TP 10
2431: [\f2count\fP]\f3.\fP
2432: Repeat the previous text modification command.
2433: .TP 10
2434: .B \(ap
2435: Invert the case of the current character and advance the cursor.
2436: .TP 10
2437: [\f2count\fP]\f3_\fP
2438: Causes the
2439: .I count\^
2440: word of the previous command to be appended and
2441: input mode entered.
2442: The last word is used
2443: if
2444: .I count\^
2445: is omitted.
2446: .TP 10
2447: .B *
2448: Causes an
2449: .B *
2450: to be appended to the current word and file name generation attempted.
2451: If no match is found,
2452: it rings the bell. Otherwise, the word is replaced
2453: by the matching pattern and input mode is entered.
2454: .RE
2455: .SS "\ \ \ \ \ Other Edit Commands"
2456: .RS
2457: Miscellaneous commands.
2458: .TP 10
2459: .B u
2460: Undo the last text modifying command.
2461: .TP 10
2462: .B U
2463: Undo all the text modifying commands performed on the line.
2464: .TP 10
2465: [\f2count\fP]\f3v\fP
2466: Returns the command
2467: .BI "fc \-e ${\s-1VISUAL\s+1:\-${\s-1EDITOR\s+1:\-vi}}" " count"
2468: in the input buffer.
2469: If
2470: .I count\^
2471: is omitted, then the current line is used.
2472: .TP 10
2473: .BI ^L
2474: Line feed and print current line.
2475: Has effect only in control mode.
2476: .TP 10
2477: .BI ^J
2478: (New\ line) Execute the current line, regardless of mode.
2479: .TP 10
2480: .BI ^M
2481: (Return) Execute the current line, regardless of mode.
2482: .TP 10
2483: .B \#
2484: Equivalent to
2485: \f3I#\fP\f2<cr>\fP.
2486: Useful for causing the current line to be
2487: inserted in the history without being executed.
2488: .RE
2489: .PD
2490: .SS Special Commands.
2491: The following simple-commands are executed in the shell process.
2492: Input/Output redirection is permitted.
2493: File descriptor 1 is the default output location.
2494: Parameter assignment lists preceding the command do not
2495: remain in effect when the command completes unless noted.
2496: .TP
2497: \f3:\fP \*(OK \f2arg\^\fP .\|.\|. \*(CK
2498: Parameter assignments remain in effect after the command completes.
2499: The command only expands parameters.
2500: A zero exit code is returned.
2501: .br
2502: .ne 2
2503: .TP
2504: \f3\|. \f2file\^\fP \*(OK \f2arg\^\fP .\|.\|. \*(CK
2505: Parameter assignments remain in effect after the command completes.
2506: Read and execute commands from
2507: .I file\^
2508: and return.
2509: The commands are executed in the current Shell environment.
2510: The search path
2511: specified by
2512: .B
2513: .SM PATH
2514: is used to find the directory containing
2515: .IR file .
2516: If any arguments
2517: .I arg\^
2518: are given,
2519: they become the positional parameters.
2520: Otherwise the positional parameters are unchanged.
2521: .TP
2522: \f3alias\fP \*(OK \f3\-tx\fP \*(CK \*(OK \f2name\fP\*(OK \f2=value\^\fP \*(CK .\|.\|. \*(CK
2523: .I Alias\^
2524: with no arguments prints the list of aliases
2525: in the form
2526: .I name=value\^
2527: on standard output.
2528: An
2529: .I alias\^
2530: is defined
2531: for each name whose
2532: .I value\^
2533: is given.
2534: A trailing space in
2535: .I value\^
2536: causes the next word to be checked for
2537: alias substitution.
2538: The
2539: .B \-t
2540: flag is used to set and list tracked aliases.
2541: The value of a tracked alias is the full pathname
2542: corresponding to the given
2543: .IR name .
2544: The value becomes undefined when the value of
2545: .SM
2546: .B PATH
2547: is reset but the aliases remained tracked.
2548: Without the
2549: .B \-t
2550: flag,
2551: for each
2552: .I name\^
2553: in the argument list
2554: for which no
2555: .I value\^
2556: is given, the name
2557: and value of the alias is printed.
2558: The
2559: .B \-x
2560: flag is used to set or print exported aliases.
2561: An exported alias is defined across sub-shell environments.
2562: Alias returns true unless a
2563: .I name\^
2564: is given for which no alias has been defined.
2565: .TP
2566: \f3bg\fP \*(OK \f3%\f2job\^\fP \*(CK
2567: This command is only built-in on systems that support job control.
2568: Puts the specified
2569: .I job\^
2570: into the background.
2571: The current job is put in the background
2572: if
2573: .I job\^
2574: is not specified.
2575: .TP
2576: \f3break\fP \*(OK \f2n\^\fP \*(CK
2577: Exit from the enclosing
2578: .BR for
2579: .BR while
2580: .BR until
2581: or
2582: .B select\^
2583: loop, if any.
2584: If
2585: .I n\^
2586: is specified then break
2587: .I n\^
2588: levels.
2589: .TP
2590: \f3continue\fP \*(OK \f2n\^\fP \*(CK
2591: Resume the next iteration of the enclosing
2592: .BR for
2593: .BR while
2594: .BR until
2595: or
2596: .B select\^
2597: loop.
2598: If
2599: .I n\^
2600: is specified then resume at the
2601: .IR n -th
2602: enclosing loop.
2603: .TP
2604: .PD 0
2605: \f3cd\fP \*(OK \f2arg\^\fP \*(CK
2606: .TP
2607: \f3cd\fP \f2old\^\fP \f2new\^\fP
2608: .PD
2609: This command can be in either of two forms.
2610: In the first form it
2611: changes the current directory to
2612: .IR arg .
2613: If
2614: .I arg\^
2615: is
2616: .B \-
2617: the directory is changed to the previous
2618: directory.
2619: The shell
2620: parameter
2621: .B
2622: .SM HOME
2623: is the default
2624: .IR arg .
2625: The parameter
2626: .SM
2627: .B PWD
2628: is set to the current directory.
2629: The shell parameter
2630: .B
2631: .SM CDPATH
2632: defines the search path for
2633: the directory containing
2634: .IR arg .
2635: Alternative directory names are separated by
2636: a colon
2637: .RB ( : ).
2638: The default path is
2639: .B <null>
2640: (specifying the current directory).
2641: Note that the current directory is specified by a null path name,
2642: which can appear immediately after the equal sign
2643: or between the colon delimiters anywhere else in the path list.
2644: If
2645: .I arg
2646: begins with a \f3/\fP then the search path
2647: is not used.
2648: Otherwise, each directory in the path is
2649: searched for
2650: .IR arg .
2651: .P
2652: The second form of
2653: .B cd
2654: substitutes the string
2655: .I new
2656: for the string
2657: .I old
2658: in the current directory name,
2659: .SM
2660: .B PWD
2661: and tries to change to this new directory.
2662: .P
2663: The
2664: .B cd\^
2665: command may not be executed by
2666: .I rsh\^.
2667: .TP
2668: \f3eval\fP \*(OK \f2arg\^\fP .\|.\|. \*(CK
2669: The arguments are read as input
2670: to the shell
2671: and the resulting command(s) executed.
2672: .TP
2673: \f3exec\fP \*(OK \f2arg\^\fP .\|.\|. \*(CK
2674: Parameter assignments remain in effect after the command completes.
2675: If
2676: .I arg\^
2677: is given,
2678: the command specified by
2679: the arguments is executed in place of this shell
2680: without creating a new process.
2681: Input/output arguments may appear and
2682: affect the current process.
2683: If no
2684: arguments are given
2685: the effect of this command is to
2686: modify file descriptors
2687: as prescribed by the input/output redirection list.
2688: In this case,
2689: any file descriptor numbers greater than 2 that are
2690: opened with this mechanism are closed when invoking
2691: another program.
2692: .TP
2693: \f3exit\fP \*(OK \f2n\^\fP \*(CK
2694: Causes the shell to exit
2695: with the exit status specified by
2696: .IR n .
2697: If
2698: .I n\^
2699: is omitted then the exit status is that of the last command executed.
2700: An end-of-file will also cause the shell to exit
2701: except for a
2702: shell which has the
2703: .I ignoreeof
2704: option (See
2705: .B set
2706: below) turned on.
2707: .TP
2708: \f3export\fP \*(OK \f2name\^\fP .\|.\|. \*(CK
2709: The given
2710: .IR name s
2711: are marked for automatic
2712: export to the
2713: .I environment\^
2714: of subsequently-executed commands.
2715: .TP
2716: .PD 0
2717: \f3fc\fP \*(OK \f3\-e \f2ename\^\fP \ \*(CK \*(OK \f3\-\f3nlr\^\f1 \*(CK \*(OK \f2first\^\fP \*(CK \*(OK \f2last\^\fP \*(CK
2718: .TP
2719: \f3fc \-e \-\fP \*(OK \f2old\fP\f3\=\fP\f2new\^\fP \*(CK \*(OK \f2command\^\fP \*(CK
2720: .PD
2721: In the first form,
2722: a range of commands from
2723: .I first\^
2724: to
2725: .I last\^
2726: is selected from the last
2727: .SM
2728: .B HISTSIZE
2729: commands that were typed at the terminal.
2730: The arguments
2731: .I first\^
2732: and
2733: .I last\^
2734: may be specified as a number or as a string.
2735: A string is used to locate the most recent command starting with
2736: the given string.
2737: A negative number is used as an offset to the current command number.
2738: If the flag
2739: .BR \-l ,
2740: is selected,
2741: the commands are listed on standard output.
2742: Otherwise, the editor program
2743: .I ename\^
2744: is invoked on a file containing these
2745: keyboard commands.
2746: If
2747: .I ename\^
2748: is not supplied, then the value of the parameter
2749: .SM
2750: .B FCEDIT
2751: (default /bin/ed)
2752: is used as the editor.
2753: When editing is complete, the edited command(s)
2754: is executed.
2755: .I last\^
2756: is not specified
2757: then it will be set to
2758: .IR first .
2759: If
2760: .I first\^
2761: is not specified
2762: the default is the previous command
2763: for editing and \-16 for listing.
2764: The flag
2765: .B \-r
2766: reverses the order of the commands and
2767: the flag
2768: .B \-n
2769: suppresses command numbers when listing.
2770: In the second form the
2771: .I command\^
2772: is re-executed after the substitution
2773: \f2old\^\fP\f3=\fP\f2new\^\fP
2774: is performed.
2775: .TP
2776: \f3fg\fP \*(OK \f3%\f2job\^\fP \*(CK
2777: This command is only built-in on systems that support job control.
2778: If
2779: .I job\^
2780: is specified it brings it to the foreground.
2781: Otherwise, the current job is
2782: brought into the foreground.
2783: .TP
2784: \f3jobs\fP \*(OK \f3\-l\^\fP \*(CK
2785: Lists the active jobs; given the
2786: .B \-l
2787: options lists process id's in addition to the normal information.
2788: .TP
2789: \f3kill\fP \*(OK \f3\-\f2sig\^\fP \*(CK \f2process\^\fP .\|.\|.
2790: Sends either the TERM (terminate) signal or the
2791: specified signal to the specified jobs or processes.
2792: Signals are either given by number or by names (as given in
2793: .I /usr/include/signal.h,
2794: stripped of the prefix ``SIG'').
2795: The signal names are listed by
2796: .BR "kill \-l'" .
2797: There is no default, saying just `kill' does not
2798: send a signal to the current job.
2799: If the signal being sent is TERM (terminate) or HUP (hangup),
2800: then the job or process will be sent a CONT (continue) signal
2801: if it is stopped.
2802: The argument
2803: .I process\^
2804: can be either a process id or a job.
2805: .TP
2806: \f3let\fP \f2arg\^\fP .\|.\|.
2807: Each
2808: .I arg
2809: is an
2810: .IR "arithmetic expression"
2811: to be evaluated.
2812: All calculations are done as long
2813: integers and no check for overflow
2814: is performed.
2815: Expressions consist of constants,
2816: named parameters, and operators.
2817: The following set of operators,
2818: listed in order of decreasing precedence,
2819: have been implemented:
2820: .RS
2821: .PD 0
2822: .TP
2823: .B \-
2824: unary minus
2825: .TP
2826: .B !
2827: logical negation
2828: .TP
2829: .B "* / %"
2830: .br
2831: multiplication, division, remainder
2832: .TP
2833: .B "+ \-"
2834: addition, subtraction
2835: .TP
2836: .B "<= >= < >"
2837: .br
2838: comparison
2839: .TP
2840: .B "== !="
2841: .br
2842: equality inequality
2843: .TP
2844: .B =
2845: arithmetic replacement
2846: .PD
2847: .PP
2848: Sub-expressions in parentheses
2849: .B (\|)
2850: are evaluated first and can be used
2851: to override the above precedence rules.
2852: The evaluation within a precedence group
2853: is from right to left for the
2854: .B =
2855: operator
2856: and from left to right for the others.
2857: .PP
2858: A parameter name must be a valid
2859: .IR identifier .
2860: When a parameter is encountered,
2861: the value associated with the
2862: parameter name is substituted and expression evaluation resumes.
2863: Up to nine levels of recursion are
2864: permitted.
2865: .PP
2866: The return code is
2867: 0 if the value of the last expression
2868: is non-zero, and 1 otherwise.
2869: .RE
2870: .TP
2871: \f3newgrp\fP \*(OK \f2arg\^\fP .\|.\|. \*(CK
2872: Equivalent to
2873: .BI "exec newgrp" " arg\^"
2874: \&.\|.\|.\^.
2875: .TP
2876: \f3print\fP \*(OK \f3\-Rnprsu\^\fP\*(OK\f2n\fP \*(CK \*(CK \*(OK \f2arg\^\fP .\|.\|. \*(CK
2877: The shell output mechanism.
2878: With no flags or with flag
2879: .BR \- ,
2880: the arguments are printed
2881: on standard output as described by
2882: .IR echo (1).
2883: In raw mode,
2884: .B \-R
2885: or
2886: .BR \-r ,
2887: the escape conventions of
2888: .I echo
2889: are ignored.
2890: The
2891: .B \-R
2892: option will print all subsequent arguments and options
2893: other than
2894: .BR \-n .
2895: The
2896: .B \-p
2897: option causes the
2898: arguments to be written onto the pipe
2899: of the process spawned with
2900: .B \(bv&
2901: instead of standard output.
2902: The
2903: .B \-s
2904: option causes the
2905: arguments to be written onto the history file
2906: instead of standard output.
2907: The
2908: .B \-u
2909: flag can be used to specify a one digit
2910: file descriptor unit number
2911: .B n\^
2912: on which the
2913: output will be placed.
2914: The default is 1.
2915: If the flag
2916: .B \-n
2917: is used, no
2918: .B new-line\^
2919: is added to the output.
2920: .TP
2921: \f3read\fP \*(OK \f3\-prsu\^\fP\*(OK \f2n\^\fP \*(CK \*(CK \*(OK \f2name\f3?\f2prompt\^\f1 \*(CK \*(OK \f2name\^\fP .\|.\|. \*(CK
2922: The shell input mechanism.
2923: One line is read and
2924: is broken up into words using the characters in
2925: .B
2926: .SM IFS
2927: as separators.
2928: In raw mode,
2929: .B \-r,
2930: a
2931: .B \e
2932: at the end of a line does not signify
2933: line continuation.
2934: The first
2935: word is assigned to the first
2936: .IR name ,
2937: the second word
2938: to the second
2939: .IR name ,
2940: etc., with leftover words assigned to the last
2941: .IR name .
2942: The
2943: .B \-p
2944: option causes the input line
2945: to be taken from the input pipe
2946: of a process spawned by the shell
2947: using
2948: .BR \(bv& .
2949: If the
2950: .B \-s
2951: fag is present,
2952: the input will be saved as a command in the history file.
2953: The flag
2954: .B \-u
2955: can be used to specify a one digit file
2956: descriptor unit to read from.
2957: The file descriptor can be opened with the
2958: .B exec\^
2959: special command.
2960: The default value of
2961: .I n\^
2962: is 0.
2963: If
2964: .IR name
2965: is omitted then
2966: .SM
2967: .B REPLY
2968: is used as the default
2969: .IR name.
2970: The return code is 0 unless an end-of-file is encountered.
2971: An end-of-file with the
2972: .B \-p
2973: option causes cleanup for this process
2974: so that another can be spawned.
2975: If the first argument contains a
2976: .BR ? ,
2977: the remainder of this word is used as a
2978: .I prompt\^
2979: when the shell is interactive.
2980: If the given file descriptor is open for writing
2981: and is a terminal device then the prompt is placed
2982: on this unit.
2983: Otherwise the prompt is issued on file descriptor 2.
2984: The return code is 0 unless an end-of-file is encountered.
2985: .TP
2986: \f3readonly\fP \*(OK \f2name\fP .\|.\|. \*(CK
2987: The given
2988: .IR names
2989: are marked
2990: readonly and these
2991: names cannot be changed
2992: by subsequent assignment.
2993: .TP
2994: \f3return\fP \*(OK \f2n\^\fP \*(CK
2995: Causes a shell
2996: .I function
2997: to return
2998: to the invoking script
2999: with the return status specified by
3000: .IR n .
3001: If
3002: .I n\^
3003: is omitted then the return status is that of the last command executed.
3004: If
3005: .B return
3006: is invoked while not in a
3007: .I function
3008: then it is the same as an
3009: .BR exit .
3010: .TP
3011: \f3set\fP \*(OK \f3\-aefhkmnostuvx\fP \*(CK \*(OK \f3\-o\fP \f2option\^\fP .\|.\|. \*(CK \*(OK \f2arg\^\fP .\|.\|. \*(CK
3012: The flags for this command have meaning as follows:
3013: .RS
3014: .PD 0
3015: .TP 8
3016: .B \-a
3017: All subsequent parameters that are defined are automatically exported.
3018: .TP 8
3019: .B \-e
3020: If the shell is non-interactive and if a command fails,
3021: execute the
3022: .SM
3023: .B ERR
3024: trap, if set,
3025: and exit immediately.
3026: This mode is disabled while reading profiles.
3027: .TP 8
3028: .B \-f
3029: Disables file name generation.
3030: .TP 8
3031: .B \-h
3032: Each command whose name is an
3033: .I identifier\^
3034: becomes a tracked alias when first encountered.
3035: .TP 8
3036: .B \-k
3037: All parameter assignment arguments are placed in the environment for a command,
3038: not just those that precede the command name.
3039: .TP 8
3040: .B \-m
3041: Background jobs will run in a separate process group
3042: and a line will print upon completion.
3043: The exit status of background jobs is reported in a completion message.
3044: On systems with job control,
3045: this flag is turned on automatically for
3046: interactive shells.
3047: .TP 8
3048: .B \-n
3049: Read commands but do not execute them.
3050: .TP 8
3051: .B \-o
3052: The following argument can be one of the following option names:
3053: .RS
3054: .TP 8
3055: .B allexport
3056: Same as
3057: .BR \-a .
3058: .TP 8
3059: .B errexit
3060: Same as
3061: .BR \-e .
3062: .TP 8
3063: .B emacs
3064: Puts you in an
3065: .I emacs
3066: style in-line editor for command entry.
3067: .TP 8
3068: .B gmacs
3069: Puts you in a
3070: .I gmacs
3071: style in-line editor for command entry.
3072: .TP 8
3073: .B ignoreeof
3074: The shell will not exit on end-of-file.
3075: The command
3076: .B exit
3077: must be used.
3078: .TP 8
3079: .B keyword
3080: Same as
3081: .BR \-k .
3082: .TP 8
3083: .B markdirs
3084: All directory names resulting from file name generation have a trailing
3085: .B /
3086: appended.
3087: .TP 8
3088: .B monitor
3089: Same as
3090: .BR \-m .
3091: .TP 8
3092: .B noexec
3093: Same as
3094: .BR \-n .
3095: .TP 8
3096: .B noglob
3097: Same as
3098: .BR \-f .
3099: .TP 8
3100: .B nounset
3101: Same as
3102: .BR \-u .
3103: .TP 8
3104: .B verbose
3105: Same as
3106: .BR \-v .
3107: .TP 8
3108: .B trackall
3109: Same as
3110: .BR \-h .
3111: .TP 8
3112: .B vi
3113: Puts you in insert mode of a
3114: .I vi\^
3115: style in-line editor
3116: until you hit escape character
3117: .BR 033 .
3118: This puts you in move mode.
3119: A return sends the line.
3120: .TP 8
3121: .B viraw
3122: Each character is processed as it is typed
3123: in
3124: .I vi\^
3125: mode.
3126: .TP 8
3127: .B xtrace
3128: Same as
3129: .BR \-x .
3130: .TP 8
3131:
3132: If no option name is supplied then the current option settings are printed.
3133: .RE
3134: .TP 8
3135: .B \-s
3136: Sort the positional parameters.
3137: .TP 8
3138: .B \-t
3139: Exit after reading and executing one command.
3140: .TP 8
3141: .B \-u
3142: Treat unset parameters as an error when substituting.
3143: .TP 8
3144: .B \-v
3145: Print shell input lines as they are read.
3146: .TP 8
3147: .B \-x
3148: Print commands and their arguments as they are executed.
3149: .TP 8
3150: .B \-
3151: Turns off
3152: .B \-x
3153: and
3154: .B \-v
3155: flags and stops examining arguments for flags.
3156: .TP 8
3157: .B \-\-
3158: Do not change any of the flags; useful in setting
3159: .B $1
3160: to a value beginning with
3161: .BR \- .
3162: If no arguments follow this flag then the positional parameters are unset.
3163: .PD
3164: .PP
3165: Using
3166: .B \+
3167: rather than
3168: .B \-
3169: causes these flags to be turned off.
3170: These flags can also be used upon invocation of the shell.
3171: The current set of flags may be found in
3172: .BR $\- .
3173: The remaining arguments are positional
3174: parameters and are assigned, in order,
3175: .if t to\p
3176: .if n to
3177: .BR $1 ,
3178: .BR $2 ,
3179: \&.\|.\|.\^.
3180: If no arguments are given then the values
3181: of all names are printed on the standard output.
3182: .RE
3183: .TP
3184: \f3shift\fP \*(OK \f2n\^\fP \*(CK
3185: .br
3186: The positional parameters from
3187: \f3$\fP\f2n\fP\f3+1\fP
3188: \&.\|.\|.
3189: are renamed
3190: .B $1
3191: \&.\|.\|.\^
3192: , default
3193: .I n\^
3194: is 1.
3195: The parameter
3196: .I n\^
3197: can be any arithmetic expression that evaluates to a non-negative
3198: number less than or equal to
3199: .BR $# .
3200: .TP
3201: \f3test\fP \*(OK \f2expr\^\fP \*(CK
3202: .br
3203: Evaluate conditional expression
3204: .IR expr .
3205: See
3206: .IR test (1)
3207: for usage and description.
3208: The arithmetic comparison operators
3209: are not restricted to integers.
3210: They allow any arithmetic expression.
3211: Four additional primitive expressions are allowed:
3212: .RS
3213: .PD 0
3214: .TP
3215: \f3\-L\fP \f2file\^\fP
3216: True if
3217: .I file\^
3218: is a symbolic link.
3219: .TP
3220: \f2file1\^\fP \f3\-nt\fP \f2file2\^\fP
3221: True if
3222: .I file1\^
3223: is newer than
3224: .IR file2 .
3225: .TP
3226: \f2file1\^\fP \f3\-ot\fP \f2file2\^\fP
3227: True if
3228: .I file1\^
3229: is older than
3230: .IR file2 .
3231: .TP
3232: \f2file1\^\fP \f3\-ef\fP \f2file2\^\fP
3233: True if
3234: .I file1\^
3235: has the same device and i-node number as
3236: .IR file2 .
3237: .PD
3238: .RE
3239: .TP
3240: \f3times\fP
3241: .br
3242: Print the accumulated user and system times for
3243: the shell and for processes
3244: run from the shell.
3245: .TP
3246: \f3trap\fP \*(OK \f2arg\^\fP \*(CK \*(OK \f2sig\^\fP \*(CK .\|.\|.
3247: .I arg\^
3248: is a command to be read and executed when the shell
3249: receives signal(s)
3250: .IR sig .
3251: (Note that
3252: .I arg\^
3253: is scanned once when
3254: the trap is set and once when the trap
3255: is taken.)
3256: Each
3257: .I sig\^
3258: can be given as a number or as the name of the signal.
3259: Trap commands are executed in order of signal number.
3260: Any attempt to set a trap on a signal that
3261: was ignored on entry to the current shell
3262: is ineffective.
3263: An attempt to trap on signal 11 (memory fault) produces an error.
3264: If
3265: .I arg\^
3266: is omitted or is
3267: .BR \- ,
3268: then all trap(s)
3269: .I sig\^
3270: are reset
3271: to their original values.
3272: If
3273: .I arg\^
3274: is the null
3275: string then this signal is ignored by the shell and by the commands
3276: it invokes.
3277: If
3278: .I sig\^
3279: is
3280: .SM
3281: .B ERR
3282: then
3283: .I arg\^
3284: will be executed whenever a command has a non-zero exit code.
3285: This trap is not inherited by functions.
3286: If
3287: .I sig\^
3288: is
3289: .B 0
3290: or
3291: .SM
3292: .B EXIT
3293: and the
3294: .B trap
3295: statement is executed inside the body of a function,
3296: then the command
3297: .I arg\^
3298: is executed
3299: after the function completes.
3300: If
3301: .I sig\^
3302: is
3303: .B 0
3304: or
3305: .SM
3306: .B EXIT
3307: for a
3308: .B trap
3309: set outside any function
3310: then the command
3311: .I arg\^
3312: is executed
3313: on exit from the shell.
3314: The
3315: .B trap
3316: command
3317: with no arguments prints a list
3318: of commands associated with each signal number.
3319: .TP
3320: \f3typeset\fP \*(OK \f3\-FLRZefilprtux\^\fP\*(OK\f2n\fP \*(CK \*(OK \f2name\fP\*(OK \f2=value\^\fP \*(CK \^ \*(CK .\|.\|. \*(CK
3321: Parameter assignments remain in effect after the command completes.
3322: When invoked inside a function,
3323: a new instance of the parameter
3324: .I name\^
3325: is created.
3326: The parameter value and type are restored
3327: when the function completes.
3328: The following list of attributes may be specified:
3329: .RS
3330: .PD 0
3331: .TP
3332: .B \-F
3333: This flag provides UNIX to host-name file mapping on non-UNIX
3334: machines.
3335: .TP
3336: .B \-L
3337: Left justify and remove leading blanks from
3338: .IR value .
3339: If
3340: .I n
3341: is non-zero it defines the width
3342: of the field,
3343: otherwise it is determined by the width of the value of
3344: first assignment.
3345: When the parameter is assigned to, it is
3346: filled on the right with blanks or truncated, if necessary, to
3347: fit into the field.
3348: Leading zeros are removed if the
3349: .B \-Z
3350: flag is also set.
3351: The
3352: .B \-R
3353: flag is turned off.
3354: .TP
3355: .B \-R
3356: Right justify and fill with leading blanks.
3357: If
3358: .I n
3359: is non-zero it defines the width
3360: of the field,
3361: otherwise it is determined by the width of the value of
3362: first assignment.
3363: The field is left filled with blanks or
3364: truncated from the end if the
3365: parameter is reassigned.
3366: The
3367: .B L
3368: flag is turned off.
3369: .TP
3370: .B \-Z
3371: Right justify and fill with leading zeros if
3372: the first non-blank character is a digit and the
3373: .B \-L
3374: flag has not been set.
3375: If
3376: .I n
3377: is non-zero it defines the width
3378: of the field,
3379: otherwise it is determined by the width of the value of
3380: first assignment.
3381: .TP
3382: .B \-e
3383: Tag the parameter as having an error.
3384: This tag is currently unused by the shell and can be
3385: set or cleared by the user.
3386: .TP
3387: .B \-f
3388: The names refer to function names rather than
3389: parameter names.
3390: No assignments can be made and the only other
3391: valid flag is
3392: .BR \-x .
3393: .TP
3394: .B \-i
3395: Parameter is an integer.
3396: This makes arithmetic faster.
3397: If
3398: .I n
3399: is non-zero it defines the output arithmetic base,
3400: otherwise the first assignment determines the output base.
3401: .TP
3402: .B \-l
3403: All upper-case characters
3404: converted to lower-case.
3405: The upper-case flag,
3406: .B \-u
3407: is turned off.
3408: .TP
3409: .B \-p
3410: The output of this command, if any, is written onto the two-way pipe
3411: .TP
3412: .B \-r
3413: The given
3414: .IR names
3415: are marked
3416: readonly and these
3417: names cannot be changed
3418: by subsequent assignment.
3419: .TP
3420: .B \-t
3421: Tags the named parameters.
3422: Tags are user definable and have no special
3423: meaning to the shell.
3424: .TP
3425: .B \-u
3426: All lower-case characters are converted
3427: to upper-case characters.
3428: The lower-case flag,
3429: .B \-l
3430: is turned off.
3431: .TP
3432: .B \-x
3433: The given
3434: .IR name s
3435: are marked for automatic
3436: export to the
3437: .I environment\^
3438: of subsequently-executed commands.
3439: .PD
3440: .PP
3441: Using
3442: .B \+
3443: rather than
3444: .B \-
3445: causes these flags to be turned off.
3446: If no
3447: .I name\^
3448: arguments are given but flags are specified,
3449: a list of
3450: .I names\^
3451: (and optionally the
3452: .I values\^
3453: )
3454: of the
3455: .I parameters\^
3456: which have these
3457: flags set
3458: is printed.
3459: (Using
3460: .B \+
3461: rather than
3462: .B \-
3463: keeps the
3464: values to be printed.)
3465: If no
3466: .IR name s
3467: and flags
3468: are given,
3469: the
3470: .I names\^
3471: and
3472: .I attributes\^
3473: of all
3474: .I parameters\^
3475: are printed.
3476: .RE
3477: .TP
3478: \f3ulimit\fP \*(OK \f3\-cdfmpt\fP \*(CK \*(OK \f2n\^\fP \*(CK
3479: .RS
3480: .PD 0
3481: .TP
3482: .B \-c
3483: imposes a size limit of
3484: .I n\^
3485: blocks on the size of core dumps
3486: (\s-1BSD\s+1 only).
3487: .TP
3488: .B \-d
3489: imposes a size limit of
3490: .I n\^
3491: blocks on the size of the data area
3492: (\s-1BSD\s+1 only).
3493: .TP
3494: .B \-f
3495: imposes a size limit of
3496: .I n\^
3497: blocks on files written by child processes (files of any size may be read).
3498: .TP
3499: .B \-m
3500: imposes a soft limit of
3501: .I n\^
3502: blocks on the size of physical memory
3503: (\s-1BSD\s+1 only).
3504: .TP
3505: .B \-p
3506: changes the pipe size to
3507: .I n\^
3508: (\s-1UNIX\s+1/\s-1RT\s+1 only).
3509: .TP
3510: .B \-t
3511: imposes a time limit of
3512: .I n\^
3513: seconds to be used by each process
3514: (\s-1BSD\s+1 only).
3515: .PD
3516: .PP
3517: If no option is given,
3518: .B \-f
3519: is assumed.
3520: If
3521: .I n\^
3522: is not given the current limit is printed.
3523: .RE
3524: .TP
3525: \f3umask\fP \*(OK \f2nnn\^\fP \*(CK
3526: The user file-creation mask is set to
3527: .I nnn\^
3528: (see
3529: .IR umask (2)).
3530: If
3531: .I nnn\^
3532: is omitted, the current value of the mask is printed.
3533: .TP
3534: \f3unalias\fP \f2name\^\fP .\|.\|.
3535: The
3536: .IR
3537: parameters
3538: given by the list of
3539: .IR name s
3540: are removed from the
3541: .I alias\^
3542: list.
3543: .TP
3544: \f3unset\fP \*(OK \f3\-f\fP \*(CK \f2name\^\fP .\|.\|.
3545: The parameters given by the list of
3546: .IR name s
3547: are unassigned,
3548: i. e.,
3549: their values and attributes are erased.
3550: Readonly variables cannot be unset.
3551: If the flag,
3552: .BR \-f ,
3553: is set, then the names refer to
3554: .I function\^
3555: names.
3556: .TP
3557: \f3wait\fP \*(OK \f2n\^\fP \*(CK
3558: Wait for the specified process and
3559: report its termination status.
3560: If
3561: .I n\^
3562: is not given then all currently active child processes are waited for.
3563: The return code from this command is that of
3564: the process waited for.
3565: .TP
3566: \f3whence\fP \*(OK \f3\-v\fP \*(CK \f2name\^\fP .\|.\|.
3567: For each
3568: .IR name ,
3569: indicate how it
3570: would be interpreted if used as a command name.
3571: .P
3572: The flag,
3573: .BR \-v ,
3574: produces a more verbose report.
3575: .SS Invocation.
3576: If the shell is invoked by
3577: .IR exec (2),
3578: and the first character of argument zero
3579: .RB ( $0 )
3580: is
3581: .BR \- ,
3582: then the shell is assumed to be a
3583: .I login
3584: shell and
3585: commands are read from
3586: .B /etc/profile
3587: and then from either
3588: .B .profile
3589: in the current directory or
3590: .BR \s-1$HOME\s+1/.profile ,
3591: if either file exists.
3592: Next, commands are read from
3593: the file named by
3594: performing parameter substitution on
3595: the value of the environment parameter
3596: .SM
3597: .B ENV
3598: if the file exists.
3599: Commands are then read as described below;
3600: the following flags are interpreted by the shell
3601: when it is invoked:
3602: .PP
3603: .PD 0
3604: .TP 10
3605: .BI \-c "\| string\^"
3606: If the
3607: .B \-c
3608: flag is present then
3609: commands are read from
3610: .IR string .
3611: .TP
3612: .B \-s
3613: If the
3614: .B \-s
3615: flag is present or if no
3616: arguments remain
3617: then commands are read from the standard input.
3618: Shell output,
3619: except for the output of some of the
3620: .I Special commands\^
3621: listed above,
3622: is written to
3623: file descriptor 2.
3624: .TP
3625: .B \-i
3626: If the
3627: .B \-i
3628: flag is present or
3629: if the shell input and output are attached to a terminal (as told by
3630: .IR gtty (2))
3631: then this shell is
3632: .IR interactive .
3633: In this case \s-1TERMINATE\s+1 is ignored (so that \f3kill 0\fP
3634: does not kill an interactive shell) and \s-1INTERRUPT\s+1 is caught and ignored
3635: (so that
3636: .B wait
3637: is interruptible).
3638: In all cases, \s-1QUIT\s+1 is ignored by the shell.
3639: .TP
3640: .B \-r
3641: If the
3642: .B \-r
3643: flag is present the shell is a restricted shell.
3644: .PD
3645: .PP
3646: The remaining flags and arguments are described under the
3647: .B set
3648: command above.
3649: .SS Rsh Only.
3650: .I Rsh
3651: is used to set up login names and execution environments whose
3652: capabilities are more controlled than those of the standard shell.
3653: The actions of
3654: .I rsh\^
3655: are identical to those of
3656: .IR sh ,
3657: except that the following are disallowed:
3658: .RS
3659: .PD 0
3660: .PP
3661: changing directory (see
3662: .IR cd (1)),
3663: .br
3664: setting the value of
3665: .SM
3666: .B SHELL
3667: or
3668: .SM
3669: .BR PATH\*S,
3670: .br
3671: specifying path or
3672: command names containing
3673: .BR / ,
3674: .br
3675: redirecting output
3676: .RB ( >
3677: and
3678: .BR >> ).
3679: .PD
3680: .RE
3681: .PP
3682: The restrictions above are enforced
3683: after \f3.profile\fP and the
3684: .SM
3685: .B ENV
3686: files are interpreted.
3687: .PP
3688: When a command to be executed is found to be a shell procedure,
3689: .I rsh\^
3690: invokes
3691: .I sh\^
3692: to execute it.
3693: Thus, it is possible to provide to the end-user shell procedures
3694: that have access to the full power of
3695: the standard shell,
3696: while imposing a limited menu of commands;
3697: this scheme assumes that the end-user does not have write and
3698: execute permissions in the same directory.
3699: .PP
3700: The net effect of these rules is that the writer of the
3701: .B .profile
3702: has complete control over user actions,
3703: by performing guaranteed setup actions
3704: and leaving the user in an appropriate directory
3705: (probably
3706: .I not\^
3707: the login directory).
3708: .PP
3709: The system administrator often sets up a directory
3710: of commands
3711: (i.e.,
3712: .BR /usr/rbin )
3713: that can be safely invoked by
3714: .IR rsh .
3715: Some systems also provide a restricted editor
3716: .IR red .
3717: .SH EXIT STATUS
3718: Errors detected by the shell, such as syntax errors,
3719: cause the shell
3720: to return a non-zero exit status.
3721: If the shell is being used non-interactively
3722: then execution of the shell file is abandoned.
3723: Otherwise, the shell returns the exit status of
3724: the last command executed (see also the
3725: .B exit
3726: command above).
3727: .SH FILES
3728: /etc/passwd
3729: .br
3730: /etc/profile
3731: .br
3732: \s-1$HOME\s+1/\f3.\fPprofile
3733: .br
3734: /tmp/sh\(**
3735: .br
3736: /dev/null
3737: .SH SEE ALSO
3738: cat(1),
3739: cd(1),
3740: echo(1),
3741: emacs(1),
3742: env(1),
3743: gmacs(1),
3744: newgrp(1),
3745: test(1),
3746: umask(1),
3747: vi(1),
3748: dup(2),
3749: exec(2),
3750: fork(2),
3751: gtty(2),
3752: pipe(2),
3753: signal(2),
3754: umask(2),
3755: ulimit(2),
3756: wait(2),
3757: rand(3),
3758: a.out(5),
3759: profile(5),
3760: environ(7).
3761: .SH CAVEATS
3762: .PP
3763: If a command which is a
3764: .I "tracked alias"
3765: is executed, and then a command with the same name is
3766: installed in a directory in the search path before the directory where the
3767: original command was found, the shell will continue to
3768: .I exec\^
3769: the original command.
3770: Use the
3771: .B \-t
3772: option of the
3773: .B alias\^
3774: command to correct this situation
3775: .PP
3776: If you move the current directory or one above it,
3777: .B pwd\^
3778: may not give the correct response.
3779: Use the
3780: .B cd\^
3781: command with a full path name
3782: to correct this situation.
3783: .PP
3784: Some very old shell scripts contain a
3785: .B ^
3786: as a synonym for the pipe character
3787: .BR \(bv .
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