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1.1 ! root 1: .TH RC 1 ! 2: .SH NAME ! 3: rc, cd, eval, exec, exit, flag, rfork, shift, wait, whatis, ., ~ \- command language ! 4: .SH SYNOPSIS ! 5: .B rc ! 6: [ ! 7: .B -srdiIlxepvV ! 8: ] ! 9: [ ! 10: .B -c command ! 11: ] ! 12: [ ! 13: .I file ! 14: [ ! 15: .I arg ... ! 16: ] ! 17: .SH DESCRIPTION ! 18: .I Rc ! 19: is the Plan 9 shell. ! 20: It executes command lines read from a terminal or a file or, with the ! 21: .B -c ! 22: flag, from ! 23: .I rc's ! 24: argument list. ! 25: .SS Command Lines ! 26: A command line is a sequence of commands, separated by ampersands or semicolons ! 27: .RB ( & ! 28: or ! 29: .BR ; ), ! 30: terminated by a newline. ! 31: The commands are executed in sequence ! 32: from left to right. ! 33: .I Rc ! 34: does not wait for a command followed by ! 35: .B & ! 36: to finish executing before starting ! 37: the following command. ! 38: Whenever a command followed by ! 39: .B & ! 40: is executed, its process id is assigned to the ! 41: .I rc ! 42: variable ! 43: .BR $apid . ! 44: Whenever a command ! 45: .I not ! 46: followed by ! 47: .B & ! 48: exits or is terminated, the ! 49: .I rc ! 50: variable ! 51: .B $status ! 52: gets the process's wait message (see ! 53: .IR wait (2)); ! 54: it will be the null string if the command was successful. ! 55: .PP ! 56: A long command line may be continued on subsequent lines by typing ! 57: a backslash ! 58: .RB ( \e ) ! 59: followed by a newline. ! 60: This sequence is treated as though it were a blank. ! 61: Backslash is not otherwise a special character. ! 62: .PP ! 63: A number-sign ! 64: .RB ( # ) ! 65: and any following characters up to (but not including) the next newline ! 66: are ignored, except in quotation marks. ! 67: .SS Simple Commands ! 68: A simple command is a sequence of arguments interspersed with I/O redirections. ! 69: If the first argument is the name of an ! 70: .I rc ! 71: function or of one of ! 72: .I rc's ! 73: built-in commands, it is executed by ! 74: .IR rc . ! 75: Otherwise if the name starts with a slash ! 76: .RB ( / ), ! 77: it must be the path name of the program to be executed. ! 78: Names containing no initial slash are searched for in ! 79: a list of directory names stored in ! 80: .BR $path . ! 81: The first executable file of the given name found ! 82: in a directory in ! 83: .B $path ! 84: is the program to be executed. ! 85: To be executable, the user must have execute permission (see ! 86: .IR stat (2)) ! 87: and the file must be either an executable binary ! 88: for the current machine's CPU type, or a shell script. ! 89: Shell scripts begin with a line containing the full path name of a shell ! 90: (usually ! 91: .BR /bin/rc ), ! 92: prefixed by ! 93: .LR #! . ! 94: .PP ! 95: The first word of a simple command cannot be a keyword unless it is ! 96: quoted or otherwise disguised. ! 97: The keywords are ! 98: .EX ! 99: for in while if not switch fn ~ ! @ ! 100: .EE ! 101: .SS Arguments and Variables ! 102: A number of constructions may be used where ! 103: .I rc's ! 104: syntax requires an argument to appear. ! 105: In many cases a construction's ! 106: value will be a list of arguments rather than a single string. ! 107: .PP ! 108: The simplest kind of argument is the unquoted word: ! 109: a sequence of one or more characters none of which is a blank, tab, ! 110: newline, or any of the following: ! 111: .EX ! 112: # ; & | ^ $ = ` ' { } ( ) < > ! 113: .EE ! 114: An unquoted word that contains any of the characters ! 115: .B * ! 116: .B ? ! 117: .B [ ! 118: is a pattern for matching against file names. ! 119: The character ! 120: .B * ! 121: matches any sequence of characters, ! 122: .B ? ! 123: matches any single character, and ! 124: .BI [ class ] ! 125: matches any character in the ! 126: .IR class . ! 127: If the first character of ! 128: .I class ! 129: is ! 130: .BR ~ , ! 131: the class is complemented. ! 132: The ! 133: .I class ! 134: may also contain pairs of characters separated by ! 135: .BR - , ! 136: standing for all characters lexically between the two. ! 137: The character ! 138: .B / ! 139: must appear explicitly in a pattern, as must the ! 140: first character of the path name components ! 141: .B . ! 142: and ! 143: .BR .. . ! 144: A pattern is replaced by a list of arguments, one for each path name matched, ! 145: except that a pattern matching no names is not replaced by the empty list, ! 146: but rather stands for itself. ! 147: Pattern matching is done after all other ! 148: operations. ! 149: Thus, ! 150: .EX ! 151: x=/tmp echo $x^/*.c ! 152: .EE ! 153: matches ! 154: .BR /tmp/*.c , ! 155: rather than matching ! 156: .B "/*.c ! 157: and then prefixing ! 158: .BR /tmp . ! 159: .PP ! 160: A quoted word is a sequence of characters surrounded by single quotes ! 161: .RB ( ' ). ! 162: A single quote is represented in a quoted word by a pair of quotes ! 163: .RB ( '' ). ! 164: .PP ! 165: Each of the following is an argument. ! 166: .PD 0 ! 167: .HP ! 168: .BI ( arguments ) ! 169: .br ! 170: The value of a sequence of arguments enclosed in parentheses is ! 171: a list comprising the members of each element of the sequence. ! 172: Argument lists have no recursive structure, although their syntax may ! 173: suggest it. ! 174: The following are entirely equivalent: ! 175: .EX ! 176: echo hi there everybody ! 177: ((echo) (hi there) everybody) ! 178: .EE ! 179: .HP ! 180: .BI $ argument ! 181: .HP ! 182: .BI $ argument ( subscript ) ! 183: .br ! 184: The ! 185: .I argument ! 186: after the ! 187: .B $ ! 188: is the name of a variable whose value is substituted. ! 189: Multiple levels ! 190: of indirection are possible, but of questionable utility. ! 191: Variable values ! 192: are lists of strings. ! 193: If ! 194: .I argument ! 195: is a number ! 196: .IR n , ! 197: the value is the ! 198: .IR n th ! 199: element of ! 200: .BR $* , ! 201: unless ! 202: .B $* ! 203: doesn't have ! 204: .I n ! 205: elements, in which case the value is empty. ! 206: If ! 207: .I argument ! 208: is followed by a parenthesized list of subscripts, the ! 209: value substituted is a list composed of the requested elements (origin 1). ! 210: The parenthesis must follow the variable name with no spaces. ! 211: Assignments to variables are described below. ! 212: .HP ! 213: .BI $# argument ! 214: .br ! 215: The value is the number of elements in the named variable. ! 216: A variable ! 217: never assigned a value has zero elements. ! 218: .HP ! 219: $"\c ! 220: .I argument ! 221: .br ! 222: The value is a single string containing the components of the named variable ! 223: separated by spaces. A variable with zero elements yields the empty string. ! 224: .HP ! 225: .BI `{ command } ! 226: .br ! 227: .I rc ! 228: executes the ! 229: .I command ! 230: and reads its standard output, splitting it into a list of arguments, ! 231: using characters in ! 232: .B $ifs ! 233: as separators. ! 234: If ! 235: .B $ifs ! 236: is not otherwise set, its value is ! 237: .BR "'\ \et\en'" . ! 238: .HP ! 239: .BI <{ command } ! 240: .HP ! 241: .BI >{ command } ! 242: .br ! 243: The ! 244: .I command ! 245: is executed asynchronously with its standard output or standard input ! 246: connected to a pipe. ! 247: The value of the argument is the name of a file ! 248: referring to the other end of the pipe. ! 249: This allows the construction of ! 250: non-linear pipelines. ! 251: For example, the following runs two commands ! 252: .B old ! 253: and ! 254: .B new ! 255: and uses ! 256: .B cmp ! 257: to compare their outputs ! 258: .EX ! 259: cmp <{old} <{new} ! 260: .EE ! 261: .HP ! 262: .IB argument ^ argument ! 263: .br ! 264: The ! 265: .B ^ ! 266: operator concatenates its two operands. ! 267: If the two operands ! 268: have the same number of components, they are concatenated pairwise. ! 269: If not, ! 270: then one operand must have one component, and the other must be non-empty, ! 271: and concatenation is distributive. ! 272: .PD ! 273: .SS Free Carets ! 274: In most circumstances, ! 275: .I rc ! 276: will insert the ! 277: .B ^ ! 278: operator automatically between words that are not separated by white space. ! 279: Whenever one of ! 280: .B $ ! 281: .B ' ! 282: .B ` ! 283: follows a quoted or unquoted word or an unquoted word follows a quoted word ! 284: with no intervening blanks or tabs, ! 285: a ! 286: .B ^ ! 287: is inserted between the two. ! 288: If an unquoted word immediately follows a ! 289: .BR $ ! 290: and contains a character other than an alphanumeric, underscore, ! 291: or ! 292: .BR * , ! 293: a ! 294: .B ^ ! 295: is inserted before the first such character. ! 296: Thus ! 297: .IP ! 298: .B cc -$flags $stem.c ! 299: .LP ! 300: is equivalent to ! 301: .IP ! 302: .B cc -^$flags $stem^.c ! 303: .SS I/O Redirections ! 304: The sequence ! 305: .BI > file ! 306: redirects the standard output file (file descriptor 1, normally the ! 307: terminal) to the named ! 308: .IR file ; ! 309: .BI >> file ! 310: appends standard output to the file. ! 311: The standard input file (file descriptor 0, also normally the terminal) ! 312: may be redirected from a file by the sequence ! 313: .BI < file \f1, ! 314: or from an inline `here document' ! 315: by the sequence ! 316: .BI << eof-marker\f1. ! 317: The contents of a here document are lines of text taken from the command ! 318: input stream up to a line containing nothing but the ! 319: .IR eof-marker , ! 320: which may be either a quoted or unquoted word. ! 321: If ! 322: .I eof-marker ! 323: is unquoted, variable names of the form ! 324: .BI $ word ! 325: have their values substituted from ! 326: .I rc's ! 327: environment. ! 328: If ! 329: .BI $ word ! 330: is followed by a caret ! 331: .RB ( ^ ), ! 332: the caret is deleted. ! 333: If ! 334: .I eof-marker ! 335: is quoted, no substitution occurs. ! 336: .PP ! 337: Redirections may be applied to a file-descriptor other than standard input ! 338: or output by qualifying the redirection operator ! 339: with a number in square brackets. ! 340: For example, the diagnostic output (file descriptor 2) ! 341: may be redirected by writing ! 342: .BR "cc junk.c >[2]junk" . ! 343: .PP ! 344: A file descriptor may be redirected to an already open descriptor by writing ! 345: .BI >[ fd0 = fd1 ] ! 346: or ! 347: .BI <[ fd0 = fd1 ]\f1. ! 348: .I Fd1 ! 349: is a previously opened file descriptor and ! 350: .I fd0 ! 351: becomes a new copy (in the sense of ! 352: .IR dup (2)) ! 353: of it. ! 354: A file descriptor may be closed by writing ! 355: .BI >[ fd0 =] ! 356: or ! 357: .BI <[ fd0 =]\f1. ! 358: .PP ! 359: Redirections are executed from left to right. ! 360: Therefore, ! 361: .B cc junk.c >/dev/null >[2=1] ! 362: and ! 363: .B cc junk.c >[2=1] >/dev/null ! 364: have different effects: the first puts standard output in ! 365: .BR /dev/null ! 366: and then puts diagnostic output in the same place, where the second ! 367: directs diagnostic output to the terminal and sends standard output to ! 368: .BR /dev/null . ! 369: .SS Compound Commands ! 370: A pair of commands separated by a pipe operator ! 371: .RB ( | ) ! 372: is a command. ! 373: The standard output of the left command is sent through a pipe ! 374: to the standard input of the right command. ! 375: The pipe operator may be decorated ! 376: to use different file descriptors. ! 377: .BI |[ fd ] ! 378: connects the output end of the pipe to file descriptor ! 379: .I fd ! 380: rather than 1. ! 381: .BI |[ fd0 = fd1 ] ! 382: connects output to ! 383: .I fd1 ! 384: of the left command and input to ! 385: .I fd0 ! 386: of the right command. ! 387: .PP ! 388: A pair of commands separated by ! 389: .B && ! 390: or ! 391: .B || ! 392: is a command. ! 393: In either case, the left command is executed and its exit status examined. ! 394: If the operator is ! 395: .B && ! 396: the right command is executed if the left command's status is null. ! 397: .B || ! 398: causes the right command to be executed if the left command's status is non-null. ! 399: .PP ! 400: The exit status of a command may be inverted (non-null is changed to null, null ! 401: is changed to non-null) by preceding it with a ! 402: .BR ! . ! 403: .PP ! 404: The ! 405: .B | ! 406: operator has highest precedence, and is left-associative (i.e. binds tighter ! 407: to the left than the right). ! 408: .B ! ! 409: has intermediate precedence, and ! 410: .B && ! 411: and ! 412: .B || ! 413: have the lowest precedence. ! 414: .PP ! 415: The unary ! 416: .B @ ! 417: operator, with precedence equal to ! 418: .BR ! , ! 419: causes its operand to be executed in a subshell. ! 420: .PP ! 421: Each of the following is a command. ! 422: .PD 0 ! 423: .HP ! 424: .B if ( ! 425: .I list ! 426: .B ) ! 427: .I command ! 428: .br ! 429: A ! 430: .I list ! 431: is a sequence of commands, separated by ! 432: .BR & , ! 433: .BR ; , ! 434: or newline. ! 435: It is executed and ! 436: if its exit status is null, the ! 437: .I command ! 438: is executed. ! 439: .HP ! 440: .B if not ! 441: .I command ! 442: .br ! 443: The immediately preceding command must have been ! 444: .BI if( list ) ! 445: .IR command . ! 446: If its condition was non-zero, the ! 447: .I command ! 448: is executed. ! 449: .HP ! 450: .BI for( name ! 451: .B in ! 452: .IB arguments ) ! 453: .I command ! 454: .HP ! 455: .BI for( name ) ! 456: .I command ! 457: .br ! 458: The ! 459: .I command ! 460: is executed once for each ! 461: .IR argument ! 462: with that argument assigned to ! 463: .IR name . ! 464: If the argument list is omitted, ! 465: .B $* ! 466: is used. ! 467: .HP ! 468: .BI while( list ) ! 469: .I command ! 470: .br ! 471: The ! 472: .I list ! 473: is executed repeatedly until its exit status is non-null. ! 474: Each time it returns null status, the ! 475: .I command ! 476: is executed. ! 477: An empty ! 478: .I list ! 479: is taken to give null status. ! 480: .HP ! 481: .BI "switch(" argument "){" list } ! 482: .br ! 483: The ! 484: .IR list ! 485: is searched for simple commands beginning with the word ! 486: .BR case . ! 487: (The search is only at the `top level' of the ! 488: .IR list . ! 489: That is, ! 490: .B cases ! 491: in nested constructs are not found.) ! 492: .I Argument ! 493: is matched against each word following ! 494: .B case ! 495: using the pattern-matching algorithm described above, except that ! 496: .B / ! 497: and the first characters of ! 498: .B . ! 499: and ! 500: .B .. ! 501: need not be matched explicitly. ! 502: When a match is found, commands in the list are executed up to the next ! 503: following ! 504: .B case ! 505: command (at the top level) or the closing brace. ! 506: .HP ! 507: .BI { list } ! 508: .br ! 509: Braces serve to alter the grouping of commands implied by operator ! 510: priorities. ! 511: The ! 512: .I body ! 513: is a sequence of commands separated by ! 514: .BR & , ! 515: .BR ; , ! 516: or newline. ! 517: .HP ! 518: .BI "fn " name { list } ! 519: .HP ! 520: .BI "fn " name ! 521: .br ! 522: The first form defines a function with the given ! 523: .IR name . ! 524: Subsequently, whenever a command whose first argument is ! 525: .I name ! 526: is encountered, the current value of ! 527: the remainder of the command's argument list will be assigned to ! 528: .BR $* , ! 529: after saving its current value, and ! 530: .I rc ! 531: will execute the ! 532: .IR list . ! 533: The second form removes ! 534: .IR name 's ! 535: function definition. ! 536: .HP ! 537: .BI "fn " note { list } ! 538: .br ! 539: .HP ! 540: .BI "fn " note ! 541: .br ! 542: A function with a special name will be called when ! 543: .I rc ! 544: receives a corresponding note; see ! 545: .IR notify (2). ! 546: The valid note names (and corresponding notes) are ! 547: .B sighup ! 548: .RB ( hangup ), ! 549: .B sigint ! 550: .RB ( interrupt ), ! 551: .BR sigalrm ! 552: .RB ( alarm ), ! 553: and ! 554: .B sigfpe ! 555: (floating point trap). ! 556: By default ! 557: .I rc ! 558: exits on receiving any signal, except when run interactively, ! 559: in which case interrupts and quits normally cause ! 560: .I rc ! 561: to stop whatever it's doing and start reading a new command. ! 562: The second form causes ! 563: .I rc ! 564: to handle a signal in the default manner. ! 565: .I Rc ! 566: recognizes an artificial note, ! 567: .BR sigexit , ! 568: which occurs when ! 569: .I rc ! 570: is about to finish executing. ! 571: .HP ! 572: .IB name = "argument command" ! 573: .br ! 574: Any command may be preceded by a sequence of assignments ! 575: interspersed with redirections. ! 576: The assignments remain in effect until the end of the command, unless ! 577: the command is empty (i.e. the assignments stand alone), in which case ! 578: they are effective until rescinded by later assignments. ! 579: .PD ! 580: .SS Built-in Commands ! 581: These commands are executed internally by ! 582: .IR rc , ! 583: usually because their execution changes or depends on ! 584: .IR rc 's ! 585: internal state. ! 586: .PD 0 ! 587: .HP ! 588: .BI . " file ..." ! 589: .br ! 590: Execute commands from ! 591: .IR file . ! 592: .B $* ! 593: is set for the duration to the remainder of the argument list following ! 594: .IR file . ! 595: .I File ! 596: is searched for using ! 597: .BR $path . ! 598: .HP ! 599: .BI builtin " command ..." ! 600: .br ! 601: Execute ! 602: .I command ! 603: as usual except that any function named ! 604: .I command ! 605: is ignored in favor of the built-in meaning. ! 606: .HP ! 607: .BI "cd [" dir "]" ! 608: .br ! 609: Change the current directory to ! 610: .IR dir . ! 611: The default argument is ! 612: .BR $home . ! 613: .I dir ! 614: is searched for in each of the directories mentioned in ! 615: .BR $cdpath . ! 616: .HP ! 617: .BI "eval [" "arg ..." "]" ! 618: .br ! 619: The arguments are concatenated separated by spaces into a single string, ! 620: read as input to ! 621: .IR rc , ! 622: and executed. ! 623: .HP ! 624: .BI "exec [" "command ..." "]" ! 625: .br ! 626: This instance of ! 627: .I rc ! 628: replaces itself with the given (non-built-in) ! 629: .IR command . ! 630: .HP ! 631: .BI "flag " f " [+-]" ! 632: .br ! 633: Either set ! 634: .RB ( + ), ! 635: clear ! 636: .RB ( - ), ! 637: or test (neither ! 638: .B + ! 639: nor ! 640: .BR - ) ! 641: the flag ! 642: .IR f , ! 643: where ! 644: .I f ! 645: is a single character, one of the command line flags (see Invocation, below). ! 646: .HP ! 647: .BI "exit [" status "]" ! 648: .br ! 649: Exit with the given exit status. ! 650: If none is given, the current value of ! 651: .B $status ! 652: is used. ! 653: .HP ! 654: .BR "rfork " [ nNeEsfF ] ! 655: .br ! 656: Become a new process group using ! 657: .BI rfork( flags ) ! 658: where ! 659: .I flags ! 660: is composed of the bitwise OR of the ! 661: .B rfork ! 662: flags specified by the option letters ! 663: (see ! 664: .IR fork (2)). ! 665: If no ! 666: .I flags ! 667: are given, they default to ! 668: .BR ens . ! 669: The ! 670: .I flags ! 671: and their meanings are: ! 672: .B n ! 673: is ! 674: .BR RFNAMEG ; ! 675: .B N ! 676: is ! 677: .BR RFCNAMEG ; ! 678: .B e ! 679: is ! 680: .BR RFENVG ; ! 681: .B E ! 682: is ! 683: .BR RFCENVG ; ! 684: .B s ! 685: is ! 686: .BR RFNOTEG ; ! 687: .B f ! 688: is ! 689: .BR RFFDG ; ! 690: and ! 691: .B F ! 692: is ! 693: .BR RFCFDG . ! 694: .HP ! 695: .BI "shift [" n "]" ! 696: .br ! 697: Delete the first ! 698: .IR n ! 699: (default 1) ! 700: elements of ! 701: .BR $* . ! 702: .HP ! 703: .BI "wait [" pid "]" ! 704: .br ! 705: Wait for the process with the given ! 706: .I pid ! 707: to exit. ! 708: If no ! 709: .I pid ! 710: is given, all outstanding processes are waited for. ! 711: .HP ! 712: .BI whatis " name ..." ! 713: .br ! 714: Print the value of each ! 715: .I name ! 716: in a form suitable for input to ! 717: .IR rc . ! 718: The output is ! 719: an assignment to any variable, ! 720: the definition of any function, ! 721: a call to ! 722: .B builtin ! 723: for any built-in command, or ! 724: the completed pathname of any executable file. ! 725: .HP ! 726: .BI ~ " subject pattern ..." ! 727: .br ! 728: The ! 729: .I subject ! 730: is matched against each ! 731: .I pattern ! 732: in sequence. ! 733: If it matches any pattern, ! 734: .B $status ! 735: is set to zero. ! 736: Otherwise, ! 737: .B $status ! 738: is set to one. ! 739: Patterns are the same as for file name matching, except that ! 740: .B / ! 741: and the first character of ! 742: .B . ! 743: and ! 744: .B .. ! 745: need not be matched explicitly. ! 746: The ! 747: .I patterns ! 748: are not subjected to ! 749: file name matching before the ! 750: .B ~ ! 751: command is executed, so they need not be enclosed in quotation marks. ! 752: .PD ! 753: .SS Environment ! 754: The ! 755: .I environment ! 756: is a list of strings made available to executing binaries by the ! 757: .B env ! 758: device ! 759: (see ! 760: .IR env (3)). ! 761: .I Rc ! 762: creates an environment entry for each variable whose value is non-empty, ! 763: and for each function. ! 764: The string for a variable entry has the variable's name followed by ! 765: .B = ! 766: and its value. ! 767: If the value has more than one component, these ! 768: are separated by ctrl-a ! 769: .RB ( '\e001' ) ! 770: characters. ! 771: The string for a function is just the ! 772: .I rc ! 773: input that defines the function. ! 774: The name of a function in the environment is the function name ! 775: preceded by ! 776: .LR fn# . ! 777: .PP ! 778: When ! 779: .I rc ! 780: starts executing it reads variable and function definitions from its ! 781: environment. ! 782: .SS Special Variables ! 783: The following variables are set or used by ! 784: .IR rc . ! 785: .PD 0 ! 786: .TP \w'\fL$promptXX'u ! 787: .B $* ! 788: Set to ! 789: .IR rc 's ! 790: argument list during initialization. ! 791: Whenever a ! 792: .B . ! 793: command or a function is executed, the current value is saved and ! 794: .B $* ! 795: receives the new argument list. ! 796: The saved value is restored on completion of the ! 797: .B . ! 798: or function. ! 799: .TP ! 800: .B $apid ! 801: Whenever a process is started asynchronously with ! 802: .BR & , ! 803: .B $apid ! 804: is set to its process id. ! 805: .TP ! 806: .B $home ! 807: The default directory for ! 808: .BR cd . ! 809: .TP ! 810: .B $ifs ! 811: The input field separators used in backquote substitutions. ! 812: If ! 813: .B $ifs ! 814: is not set in ! 815: .IR rc 's ! 816: environment, it is initialized to blank, tab and newline. ! 817: .TP ! 818: .B $path ! 819: The search path used to find commands and input files ! 820: for the ! 821: .B . ! 822: command. ! 823: If not set in the environment, it is initialized by ! 824: .BR "path=(.\ /bin)" . ! 825: Its use is discouraged; instead use ! 826: .IR bind (1) ! 827: to build a ! 828: .B /bin ! 829: containing what's needed. ! 830: .TP ! 831: .B $pid ! 832: Set during initialization to ! 833: .IR rc 's ! 834: process id. ! 835: .TP ! 836: .B $prompt ! 837: When ! 838: .I rc ! 839: is run interactively, the first component of ! 840: .B $prompt ! 841: is printed before reading each command. ! 842: The second component is printed whenever a newline is typed and more lines ! 843: are required to complete the command. ! 844: If not set in the environment, it is initialized by ! 845: .BR "prompt=('%\ '\ '\ ')" . ! 846: .TP ! 847: .B $status ! 848: Set to the wait message of the last-executed program. ! 849: (unless started with ! 850: .BR &). ! 851: .B ! ! 852: and ! 853: .B ~ ! 854: also change ! 855: .BR $status . ! 856: Its value is used to control execution in ! 857: .BR && , ! 858: .BR || , ! 859: .B if ! 860: and ! 861: .B while ! 862: commands. ! 863: When ! 864: .I rc ! 865: exits at end-of-file of its input or on executing an ! 866: .B exit ! 867: command with no argument, ! 868: .B $status ! 869: is its exit status. ! 870: .PD ! 871: .SS Invocation ! 872: If ! 873: .I rc ! 874: is started with no arguments it reads commands from standard input. ! 875: Otherwise its first non-flag argument is the name of a file from which ! 876: to read commands (but see ! 877: .B -c ! 878: below). ! 879: Subsequent arguments become the initial value of ! 880: .BR $* . ! 881: .I Rc ! 882: accepts the following command-line flags. ! 883: .PD 0 ! 884: .TP \w'\fL-c\ \fIstring\fLXX'u ! 885: .BI -c " string" ! 886: Commands are read from ! 887: .IR string . ! 888: .TP ! 889: .B -s ! 890: Print out exit status after any command where the status is non-null. ! 891: .TP ! 892: .B -e ! 893: Exit if ! 894: .B $status ! 895: is non-null after executing a simple command. ! 896: .TP ! 897: .B -i ! 898: If ! 899: .B -i ! 900: is present, or ! 901: .I rc ! 902: is given no arguments and its standard input is a terminal, ! 903: it runs interactively. ! 904: Commands are prompted for using ! 905: .BR $prompt . ! 906: .TP ! 907: .B -I ! 908: Makes sure ! 909: .I rc ! 910: is not run interactively. ! 911: .TP ! 912: .B -l ! 913: If ! 914: .B -l ! 915: is given or the first character of argument zero is ! 916: .BR - , ! 917: .I rc ! 918: reads commands from ! 919: .BR $home/lib/profile , ! 920: if it exists, before reading its normal input. ! 921: .TP ! 922: .B -p ! 923: A no-op. ! 924: .TP ! 925: .B -d ! 926: A no-op. ! 927: .TP ! 928: .B -v ! 929: Echo input on file descriptor 2 as it is read. ! 930: .TP ! 931: .B -x ! 932: Print each simple command before executing it. ! 933: .TP ! 934: .B -r ! 935: Print debugging information (internal form of commands ! 936: as they are executed). ! 937: .PD ! 938: .SH SOURCE ! 939: .B /sys/src/cmd/rc ! 940: .SH "SEE ALSO" ! 941: Tom Duff, ! 942: ``Rc \- The Plan 9 Shell''. ! 943: .SH BUGS ! 944: There should be a way to match patterns against whole lists rather than ! 945: just single strings. ! 946: .br ! 947: Using ! 948: .B ~ ! 949: to check the value of ! 950: .B $status ! 951: changes ! 952: .BR $status . ! 953: .br ! 954: Functions that use here documents don't work.
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