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1.1 root 1: .TH SED 1
2: .SH NAME
3: sed \- stream editor
4: .SH SYNOPSIS
5: .B sed
6: [
7: .B -n
8: ]
9: [
10: .B -g
11: ]
12: [
13: .B -e
14: .I script
15: ]
16: [
17: .B -f
18: .I sfile
19: ]
20: [
21: .I file ...
22: ]
23: .SH DESCRIPTION
24: .I Sed
25: copies the named
26: .I files
27: (standard input default) to the standard output,
28: edited according to a script of commands.
29: The
30: .B -f
31: option causes the script to be taken from file
32: .IR sfile ;
33: these options accumulate.
34: If there is just one
35: .B -e
36: option and no
37: .BR -f 's,
38: the flag
39: .B -e
40: may be omitted.
41: The
42: .B -n
43: option suppresses the default output;
44: .B -g
45: causes all substitutions to be global, as if suffixed
46: .BR g .
47: .PP
48: A script consists of editing commands, one per line,
49: of the following form:
50: .IP
51: [\fIaddress\fR [\fL,\fI address\fR] ] \fIfunction\fR [\fIargument\fR ...]
52: .PP
53: In normal operation
54: .I sed
55: cyclically copies a line of input into a
56: .I pattern space
57: (unless there is something left after
58: a
59: .L D
60: command),
61: applies in sequence
62: all commands whose
63: .I addresses
64: select that pattern space,
65: and at the end of the script copies the pattern space
66: to the standard output (except under
67: .BR -n )
68: and deletes the pattern space.
69: .PP
70: An
71: .I address
72: is either a decimal number that counts
73: input lines cumulatively across files, a
74: .L $
75: that
76: addresses the last line of input, or a context address,
77: .BI / regular-expression / \f1,
78: in the style of
79: .IR regexp (6),
80: with the added convention that
81: .L \en
82: matches a
83: newline embedded in the pattern space.
84: .PP
85: A command line with no addresses selects every pattern space.
86: .PP
87: A command line with
88: one address selects each pattern space that matches the address.
89: .PP
90: A command line with
91: two addresses selects the inclusive range from the first
92: pattern space that matches the first address through
93: the next pattern space that matches
94: the second.
95: (If the second address is a number less than or equal
96: to the line number first selected, only one
97: line is selected.)
98: Thereafter the process is repeated, looking again for the
99: first address.
100: .PP
101: Editing commands can be applied to non-selected pattern
102: spaces by use of the negation function
103: .L !
104: (below).
105: .PP
106: An argument denoted
107: .I text
108: consists of one or more lines,
109: all but the last of which end with
110: .L \e
111: to hide the
112: newline.
113: Backslashes in text are treated like backslashes
114: in the replacement string of an
115: .L s
116: command,
117: and may be used to protect initial blanks and tabs
118: against the stripping that is done on
119: every script line.
120: .PP
121: An argument denoted
122: .I rfile
123: or
124: .I wfile
125: must terminate the command
126: line and must be preceded by exactly one blank.
127: Each
128: .I wfile
129: is created before processing begins.
130: There can be at most 120 distinct
131: .I wfile
132: arguments.
133: .TP \w'\fL!\ \fIfunction\fLXXX'u
134: .B a\e
135: .br
136: .ns
137: .TP
138: .I text
139: Append.
140: Place
141: .I text
142: on the output before
143: reading the next input line.
144: .TP
145: .BI b " label"
146: Branch to the
147: .B :
148: command bearing the
149: .IR label .
150: If
151: .I label
152: is empty, branch to the end of the script.
153: .TP
154: .B c\e
155: .br
156: .ns
157: .TP
158: .I text
159: Change.
160: Delete the pattern space.
161: With 0 or 1 address or at the end of a 2-address range, place
162: .I text
163: on the output.
164: Start the next cycle.
165: .TP
166: .B d
167: Delete the pattern space.
168: Start the next cycle.
169: .TP
170: .B D
171: Delete the initial segment of the
172: pattern space through the first newline.
173: Start the next cycle.
174: .TP
175: .B g
176: Replace the contents of the pattern space
177: by the contents of the hold space.
178: .TP
179: .B G
180: Append the contents of the hold space to the pattern space.
181: .TP
182: .B h
183: Replace the contents of the hold space by the contents of the pattern space.
184: .TP
185: .B H
186: Append the contents of the pattern space to the hold space.
187: .ne 3
188: .TP
189: .B i\e
190: .br
191: .ns
192: .TP
193: .I text
194: Insert.
195: Place
196: .I text
197: on the standard output.
198: .TP
199: .B n
200: Copy the pattern space to the standard output.
201: Replace the pattern space with the next line of input.
202: .TP
203: .B N
204: Append the next line of input to the pattern space
205: with an embedded newline.
206: (The current line number changes.)
207: .TP
208: .B p
209: Print.
210: Copy the pattern space to the standard output.
211: .TP
212: .B P
213: Copy the initial segment of the pattern space through
214: the first newline to the standard output.
215: .TP
216: .B q
217: Quit.
218: Branch to the end of the script.
219: Do not start a new cycle.
220: .TP
221: .BI r " rfile"
222: Read the contents of
223: .IR rfile .
224: Place them on the output before reading
225: the next input line.
226: .TP
227: .B s/\fIregular-expression\fP/\fIreplacement\fP/\fIflags
228: Substitute the
229: .I replacement
230: string for instances of the
231: .I regular-expression
232: in the pattern space.
233: Any character may be used instead of
234: .LR / .
235: For a fuller description see
236: .IR regexp (6).
237: .I Flags
238: is zero or more of
239: .RS
240: .TP
241: .B g
242: Global.
243: Substitute for all non-overlapping instances of the
244: .I regular expression
245: rather than just the
246: first one.
247: .TP
248: .B p
249: Print the pattern space if a replacement was made.
250: .TP
251: .BI w " wfile"
252: Write.
253: Append the pattern space to
254: .I wfile
255: if a replacement
256: was made.
257: .RE
258: .TP
259: .BI t " label"
260: Test.
261: Branch to the
262: .L :
263: command bearing the
264: .I label
265: if any
266: substitutions have been made since the most recent
267: reading of an input line or execution of a
268: .LR t .
269: If
270: .I label
271: is empty, branch to the end of the script.
272: .TP
273: .B w
274: .I wfile
275: .br
276: Write.
277: Append the pattern space to
278: .IR wfile .
279: .TP
280: .B x
281: Exchange the contents of the pattern and hold spaces.
282: .TP
283: .B y/\fIstring1\fP/\fIstring2\fP/
284: Transform.
285: Replace all occurrences of characters in
286: .I string1
287: with the corresponding character in
288: .IR string2 .
289: The lengths of
290: .I
291: string1
292: and
293: .I string2
294: must be equal.
295: .TP
296: .BI ! "function"
297: Don't.
298: Apply the
299: .I function
300: (or group, if
301: .I function
302: is
303: .LR { )
304: only to lines
305: .I not
306: selected by the address(es).
307: .TP
308: .BI : " label"
309: This command does nothing; it bears a
310: .I label
311: for
312: .B b
313: and
314: .B t
315: commands to branch to.
316: .TP
317: .B =
318: Place the current line number on the standard output as a line.
319: .TP
320: .B {
321: Execute the following commands through a matching
322: .L }
323: only when the pattern space is selected.
324: .TP
325: .B " "
326: An empty command is ignored.
327: .ne 4
328: .SH EXAMPLES
329: .TP
330: .B sed 10q file
331: Print the first 10 lines of the file.
332: .TP
333: .B sed '/^$/d'
334: Delete empty lines from standard input.
335: .TP
336: .B sed 's/UNIX/& system/g'
337: Replace every instance of
338: .L UNIX
339: by
340: .LR "UNIX system" .
341: .PP
342: .EX
343: sed 's/ *$// \fRdrop trailing blanks\fP
344: /^$/d \fRdrop empty lines\fP
345: s/ */\e \fRreplace blanks by newlines\fP
346: /g
347: /^$/d' chapter*
348: .EE
349: .ns
350: .IP
351: Print the files
352: .BR chapter1 ,
353: .BR chapter2 ,
354: etc. one word to a line.
355: .PP
356: .EX
357: nroff -ms manuscript | sed '
358: ${
359: /^$/p \fRif last line of file is empty, print it\fP
360: }
361: //N \fRif current line is empty, append next line\fP
362: /^\en$/D' \fRif two lines are empty, delete the first\fP
363: .EE
364: .ns
365: .IP
366: Delete all but one of each group of empty lines from a
367: formatted manuscript.
368: .SH SOURCE
369: .B /sys/src/cmd/sed.c
370: .SH SEE ALSO
371: .IR ed (1),
372: .IR grep (1),
373: .IR awk (1),
374: .IR lex (1),
375: .IR sam (1),
376: .IR regexp (6)
377: .br
378: L. E. McMahon,
379: `SED \(em A Non-interactive Text Editor',
380: Unix Research System Programmer's Manual, Volume 2.
381: .SH BUGS
382: If input is from a pipe, buffering may consume
383: characters beyond a line on which a
384: .L q
385: command is executed.
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