Annotation of src/usr.bin/awk/awk.1, Revision 1.40
1.40 ! jmc 1: .\" $OpenBSD: awk.1,v 1.39 2011/03/22 15:55:43 jmc Exp $
1.11 jmc 2: .\"
3: .\" Copyright (C) Lucent Technologies 1997
4: .\" All Rights Reserved
1.12 jmc 5: .\"
1.11 jmc 6: .\" Permission to use, copy, modify, and distribute this software and
7: .\" its documentation for any purpose and without fee is hereby
8: .\" granted, provided that the above copyright notice appear in all
9: .\" copies and that both that the copyright notice and this
10: .\" permission notice and warranty disclaimer appear in supporting
11: .\" documentation, and that the name Lucent Technologies or any of
12: .\" its entities not be used in advertising or publicity pertaining
13: .\" to distribution of the software without specific, written prior
14: .\" permission.
1.12 jmc 15: .\"
1.11 jmc 16: .\" LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
17: .\" INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
18: .\" IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
19: .\" SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
20: .\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
21: .\" IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
22: .\" ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
23: .\" THIS SOFTWARE.
24: .\"
1.40 ! jmc 25: .Dd $Mdocdate: March 22 2011 $
1.7 aaron 26: .Dt AWK 1
27: .Os
28: .Sh NAME
29: .Nm awk
30: .Nd pattern-directed scanning and processing language
31: .Sh SYNOPSIS
32: .Nm awk
1.16 jmc 33: .Op Fl safe
34: .Op Fl V
35: .Op Fl d Ns Op Ar n
1.7 aaron 36: .Op Fl F Ar fs
1.38 schwarze 37: .Op Fl v Ar var Ns = Ns Ar value
1.18 jmc 38: .Op Ar prog | Fl f Ar progfile
1.7 aaron 39: .Ar
40: .Sh DESCRIPTION
41: .Nm
1.1 tholo 42: scans each input
1.7 aaron 43: .Ar file
1.1 tholo 44: for lines that match any of a set of patterns specified literally in
1.7 aaron 45: .Ar prog
1.16 jmc 46: or in one or more files specified as
1.7 aaron 47: .Fl f Ar progfile .
1.16 jmc 48: With each pattern there can be an associated action that will be performed
1.1 tholo 49: when a line of a
1.7 aaron 50: .Ar file
1.1 tholo 51: matches the pattern.
52: Each line is matched against the
53: pattern portion of every pattern-action statement;
54: the associated action is performed for each matched pattern.
1.6 aaron 55: The file name
1.16 jmc 56: .Sq -
1.1 tholo 57: means the standard input.
58: Any
1.7 aaron 59: .Ar file
1.1 tholo 60: of the form
1.16 jmc 61: .Ar var Ns = Ns Ar value
1.1 tholo 62: is treated as an assignment, not a filename,
63: and is executed at the time it would have been opened if it were a filename.
1.16 jmc 64: .Pp
65: The options are as follows:
1.20 jmc 66: .Bl -tag -width "-safe "
1.16 jmc 67: .It Fl d Ns Op Ar n
68: Debug mode.
69: Set debug level to
70: .Ar n ,
71: or 1 if
72: .Ar n
73: is not specified.
74: A value greater than 1 causes
75: .Nm
76: to dump core on fatal errors.
77: .It Fl F Ar fs
78: Define the input field separator to be the regular expression
1.7 aaron 79: .Ar fs .
1.25 jmc 80: .It Fl f Ar progfile
1.16 jmc 81: Read program code from the specified file
1.25 jmc 82: .Ar progfile
1.16 jmc 83: instead of from the command line.
84: .It Fl safe
85: Disable file output
1.17 jmc 86: .Pf ( Ic print No > ,
87: .Ic print No >> ) ,
1.7 aaron 88: process creation
89: .Po
1.17 jmc 90: .Ar cmd | Ic getline ,
1.40 ! jmc 91: .Ic print | ,
1.17 jmc 92: .Ic system
1.7 aaron 93: .Pc
94: and access to the environment
1.17 jmc 95: .Pf ( Va ENVIRON ;
1.18 jmc 96: see the section on variables below).
1.17 jmc 97: This is a first
1.16 jmc 98: .Pq and not very reliable
99: approximation to a
1.7 aaron 100: .Dq safe
101: version of
1.16 jmc 102: .Nm .
103: .It Fl V
104: Print the version number of
105: .Nm
106: to standard output and exit.
107: .It Fl v Ar var Ns = Ns Ar value
108: Assign
109: .Ar value
110: to variable
111: .Ar var
112: before
113: .Ar prog
114: is executed;
115: any number of
116: .Fl v
117: options may be present.
118: .El
1.7 aaron 119: .Pp
1.18 jmc 120: The input is normally made up of input lines
121: .Pq records
122: separated by newlines, or by the value of
123: .Va RS .
124: If
125: .Va RS
126: is null, then any number of blank lines are used as the record separator,
127: and newlines are used as field separators
128: (in addition to the value of
129: .Va FS ) .
130: This is convenient when working with multi-line records.
131: .Pp
1.7 aaron 132: An input line is normally made up of fields separated by whitespace,
1.18 jmc 133: or by the regular expression
1.7 aaron 134: .Va FS .
1.1 tholo 135: The fields are denoted
1.7 aaron 136: .Va $1 , $2 , ... ,
137: while
138: .Va $0
1.1 tholo 139: refers to the entire line.
140: If
1.7 aaron 141: .Va FS
1.1 tholo 142: is null, the input line is split into one field per character.
1.7 aaron 143: .Pp
1.18 jmc 144: Normally, any number of blanks separate fields.
145: In order to set the field separator to a single blank, use the
146: .Fl F
147: option with a value of
148: .Sq [\ \&] .
149: If a field separator of
150: .Sq t
151: is specified,
152: .Nm
153: treats it as if
154: .Sq \et
155: had been specified and uses
156: .Aq TAB
157: as the field separator.
158: In order to use a literal
159: .Sq t
160: as the field separator, use the
161: .Fl F
162: option with a value of
163: .Sq [t] .
164: .Pp
1.1 tholo 165: A pattern-action statement has the form
1.7 aaron 166: .Pp
167: .D1 Ar pattern Ic \&{ Ar action Ic \&}
168: .Pp
1.6 aaron 169: A missing
1.7 aaron 170: .Ic \&{ Ar action Ic \&}
1.1 tholo 171: means print the line;
172: a missing pattern always matches.
173: Pattern-action statements are separated by newlines or semicolons.
1.7 aaron 174: .Pp
1.18 jmc 175: Newlines are permitted after a terminating statement or following a comma
176: .Pq Sq ,\& ,
177: an open brace
178: .Pq Sq { ,
179: a logical AND
180: .Pq Sq && ,
181: a logical OR
182: .Pq Sq || ,
183: after the
184: .Sq do
185: or
186: .Sq else
187: keywords,
188: or after the closing parenthesis of an
189: .Sq if ,
190: .Sq for ,
191: or
192: .Sq while
193: statement.
194: Additionally, a backslash
195: .Pq Sq \e
196: can be used to escape a newline between tokens.
197: .Pp
1.1 tholo 198: An action is a sequence of statements.
199: A statement can be one of the following:
1.35 jmc 200: .Pp
201: .Bl -tag -width Ds -offset indent -compact
202: .It Xo Ic if ( Ar expression ) Ar statement
1.7 aaron 203: .Op Ic else Ar statement
204: .Xc
1.35 jmc 205: .It Ic while ( Ar expression ) Ar statement
206: .It Xo Ic for
207: .No ( Ar expression ; expression ; expression ) statement
208: .Xc
209: .It Xo Ic for
210: .No ( Ar var Ic in Ar array ) statement
211: .Xc
212: .It Xo Ic do
213: .Ar statement Ic while ( Ar expression )
214: .Xc
215: .It Ic break
216: .It Ic continue
217: .It Xo Ic {
218: .Op Ar statement ...
219: .Ic }
220: .Xc
221: .It Xo Ar expression
222: .No # commonly
223: .Ar var No = Ar expression
1.7 aaron 224: .Xc
1.35 jmc 225: .It Xo Ic print
1.7 aaron 226: .Op Ar expression-list
1.17 jmc 227: .Op > Ns Ar expression
1.7 aaron 228: .Xc
1.35 jmc 229: .It Xo Ic printf Ar format
1.7 aaron 230: .Op Ar ... , expression-list
1.17 jmc 231: .Op > Ns Ar expression
1.7 aaron 232: .Xc
1.35 jmc 233: .It Ic return Op Ar expression
234: .It Xo Ic next
235: .No # skip remaining patterns on this input line
236: .Xc
237: .It Xo Ic nextfile
238: .No # skip rest of this file, open next, start at top
239: .Xc
240: .It Xo Ic delete
241: .Sm off
242: .Ar array Ic \&[ Ar expression Ic \&]
243: .Sm on
244: .No # delete an array element
1.7 aaron 245: .Xc
1.35 jmc 246: .It Xo Ic delete Ar array
247: .No # delete all elements of array
1.7 aaron 248: .Xc
1.35 jmc 249: .It Xo Ic exit
1.7 aaron 250: .Op Ar expression
1.35 jmc 251: .No # exit immediately; status is Ar expression
1.7 aaron 252: .Xc
1.35 jmc 253: .El
1.7 aaron 254: .Pp
1.1 tholo 255: Statements are terminated by
256: semicolons, newlines or right braces.
257: An empty
1.7 aaron 258: .Ar expression-list
1.1 tholo 259: stands for
1.7 aaron 260: .Ar $0 .
261: String constants are quoted
262: .Li \&"" ,
1.20 jmc 263: with the usual C escapes recognized within
264: (see
265: .Xr printf 1
266: for a complete list of these).
1.1 tholo 267: Expressions take on string or numeric values as appropriate,
268: and are built using the operators
1.7 aaron 269: .Ic + \- * / % ^
1.20 jmc 270: .Pq exponentiation ,
271: and concatenation
272: .Pq indicated by whitespace .
1.1 tholo 273: The operators
1.16 jmc 274: .Ic \&! ++ \-\- += \-= *= /= %= ^=
275: .Ic > >= < <= == != ?:
1.1 tholo 276: are also available in expressions.
277: Variables may be scalars, array elements
278: (denoted
1.7 aaron 279: .Li x[i] )
1.1 tholo 280: or fields.
281: Variables are initialized to the null string.
282: Array subscripts may be any string,
283: not necessarily numeric;
284: this allows for a form of associative memory.
285: Multiple subscripts such as
1.7 aaron 286: .Li [i,j,k]
1.1 tholo 287: are permitted; the constituents are concatenated,
288: separated by the value of
1.17 jmc 289: .Va SUBSEP
1.31 deraadt 290: .Pq see the section on variables below .
1.7 aaron 291: .Pp
1.1 tholo 292: The
1.7 aaron 293: .Ic print
1.1 tholo 294: statement prints its arguments on the standard output
295: (or on a file if
1.17 jmc 296: .Pf > Ns Ar file
1.1 tholo 297: or
1.17 jmc 298: .Pf >> Ns Ar file
1.1 tholo 299: is present or on a pipe if
1.17 jmc 300: .Pf |\ \& Ar cmd
1.1 tholo 301: is present), separated by the current output field separator,
302: and terminated by the output record separator.
1.7 aaron 303: .Ar file
1.1 tholo 304: and
1.7 aaron 305: .Ar cmd
1.1 tholo 306: may be literal names or parenthesized expressions;
307: identical string values in different statements denote
308: the same open file.
309: The
1.7 aaron 310: .Ic printf
1.1 tholo 311: statement formats its expression list according to the format
312: (see
1.28 jmc 313: .Xr printf 1 ) .
1.18 jmc 314: .Pp
315: Patterns are arbitrary Boolean combinations
316: (with
317: .Ic "\&! || &&" )
318: of regular expressions and
319: relational expressions.
1.22 jmc 320: .Nm
321: supports extended regular expressions
322: .Pq EREs .
323: See
324: .Xr re_format 7
325: for more information on regular expressions.
1.18 jmc 326: Isolated regular expressions
327: in a pattern apply to the entire line.
328: Regular expressions may also occur in
329: relational expressions, using the operators
330: .Ic ~
331: and
332: .Ic !~ .
333: .Pf / Ns Ar re Ns /
334: is a constant regular expression;
335: any string (constant or variable) may be used
336: as a regular expression, except in the position of an isolated regular expression
337: in a pattern.
338: .Pp
339: A pattern may consist of two patterns separated by a comma;
340: in this case, the action is performed for all lines
341: from an occurrence of the first pattern
342: through an occurrence of the second.
343: .Pp
344: A relational expression is one of the following:
1.35 jmc 345: .Pp
346: .Bl -tag -width Ds -offset indent -compact
347: .It Ar expression matchop regular-expression
348: .It Ar expression relop expression
349: .It Ar expression Ic in Ar array-name
350: .It Xo Ic \&( Ns
1.18 jmc 351: .Ar expr , expr , \&... Ns Ic \&) in
1.35 jmc 352: .Ar array-name
1.18 jmc 353: .Xc
1.35 jmc 354: .El
1.18 jmc 355: .Pp
356: where a
357: .Ar relop
358: is any of the six relational operators in C, and a
359: .Ar matchop
360: is either
361: .Ic ~
362: (matches)
363: or
364: .Ic !~
365: (does not match).
366: A conditional is an arithmetic expression,
367: a relational expression,
368: or a Boolean combination
369: of these.
370: .Pp
371: The special patterns
372: .Ic BEGIN
373: and
374: .Ic END
375: may be used to capture control before the first input line is read
376: and after the last.
377: .Ic BEGIN
378: and
379: .Ic END
380: do not combine with other patterns.
381: .Pp
382: Variable names with special meanings:
383: .Pp
1.20 jmc 384: .Bl -tag -width "FILENAME " -compact
1.18 jmc 385: .It Va ARGC
386: Argument count, assignable.
387: .It Va ARGV
388: Argument array, assignable;
389: non-null members are taken as filenames.
390: .It Va CONVFMT
391: Conversion format when converting numbers
392: (default
393: .Qq Li %.6g ) .
394: .It Va ENVIRON
395: Array of environment variables; subscripts are names.
396: .It Va FILENAME
397: The name of the current input file.
398: .It Va FNR
399: Ordinal number of the current record in the current file.
400: .It Va FS
401: Regular expression used to separate fields; also settable
402: by option
403: .Fl F Ar fs .
404: .It Va NF
405: Number of fields in the current record.
406: .Va $NF
407: can be used to obtain the value of the last field in the current record.
408: .It Va NR
409: Ordinal number of the current record.
410: .It Va OFMT
411: Output format for numbers (default
412: .Qq Li %.6g ) .
413: .It Va OFS
414: Output field separator (default blank).
415: .It Va ORS
416: Output record separator (default newline).
417: .It Va RLENGTH
418: The length of the string matched by the
419: .Fn match
420: function.
421: .It Va RS
422: Input record separator (default newline).
423: .It Va RSTART
424: The starting position of the string matched by the
425: .Fn match
426: function.
427: .It Va SUBSEP
428: Separates multiple subscripts (default 034).
429: .El
1.17 jmc 430: .Sh FUNCTIONS
431: The awk language has a variety of built-in functions:
1.30 jmc 432: arithmetic, string, input/output, general, and bit-operation.
433: .Pp
434: Functions may be defined (at the position of a pattern-action statement)
435: thusly:
436: .Pp
437: .Dl function foo(a, b, c) { ...; return x }
438: .Pp
439: Parameters are passed by value if scalar, and by reference if array name;
440: functions may be called recursively.
441: Parameters are local to the function; all other variables are global.
442: Thus local variables may be created by providing excess parameters in
443: the function definition.
1.17 jmc 444: .Ss Arithmetic Functions
445: .Bl -tag -width "atan2(y, x)"
446: .It Fn atan2 y x
447: Return the arctangent of
448: .Fa y Ns / Ns Fa x
449: in radians.
450: .It Fn cos x
451: Return the cosine of
452: .Fa x ,
453: where
454: .Fa x
455: is in radians.
456: .It Fn exp x
457: Return the exponential of
458: .Fa x .
459: .It Fn int x
460: Return
461: .Fa x
462: truncated to an integer value.
463: .It Fn log x
464: Return the natural logarithm of
465: .Fa x .
1.7 aaron 466: .It Fn rand
1.17 jmc 467: Return a random number,
468: .Fa n ,
469: such that
470: .Sm off
471: .Pf 0 \*(Le Fa n No \*(Lt 1 .
472: .Sm on
473: .It Fn sin x
474: Return the sine of
475: .Fa x ,
476: where
477: .Fa x
478: is in radians.
479: .It Fn sqrt x
480: Return the square root of
481: .Fa x .
482: .It Fn srand expr
1.16 jmc 483: Sets seed for
1.7 aaron 484: .Fn rand
1.17 jmc 485: to
486: .Fa expr
1.1 tholo 487: and returns the previous seed.
1.17 jmc 488: If
489: .Fa expr
490: is omitted, the time of day is used instead.
491: .El
492: .Ss String Functions
493: .Bl -tag -width "split(s, a, fs)"
494: .It Fn gsub r t s
495: The same as
496: .Fn sub
497: except that all occurrences of the regular expression are replaced.
498: .Fn gsub
499: returns the number of replacements.
1.7 aaron 500: .It Fn index s t
1.16 jmc 501: The position in
1.7 aaron 502: .Fa s
1.1 tholo 503: where the string
1.7 aaron 504: .Fa t
1.1 tholo 505: occurs, or 0 if it does not.
1.17 jmc 506: .It Fn length s
507: The length of
508: .Fa s
509: taken as a string,
510: or of
511: .Va $0
512: if no argument is given.
1.7 aaron 513: .It Fn match s r
1.16 jmc 514: The position in
1.7 aaron 515: .Fa s
1.1 tholo 516: where the regular expression
1.7 aaron 517: .Fa r
1.1 tholo 518: occurs, or 0 if it does not.
1.17 jmc 519: The variable
1.7 aaron 520: .Va RSTART
1.17 jmc 521: is set to the starting position of the matched string
522: .Pq which is the same as the returned value
523: or zero if no match is found.
524: The variable
1.7 aaron 525: .Va RLENGTH
1.17 jmc 526: is set to the length of the matched string,
527: or \-1 if no match is found.
1.7 aaron 528: .It Fn split s a fs
1.16 jmc 529: Splits the string
1.7 aaron 530: .Fa s
1.1 tholo 531: into array elements
1.7 aaron 532: .Va a[1] , a[2] , ... , a[n]
1.1 tholo 533: and returns
1.7 aaron 534: .Va n .
1.1 tholo 535: The separation is done with the regular expression
1.7 aaron 536: .Ar fs
1.1 tholo 537: or with the field separator
1.7 aaron 538: .Va FS
1.1 tholo 539: if
1.7 aaron 540: .Ar fs
1.1 tholo 541: is not given.
542: An empty string as field separator splits the string
543: into one array element per character.
1.17 jmc 544: .It Fn sprintf fmt expr ...
545: The string resulting from formatting
546: .Fa expr , ...
547: according to the
1.28 jmc 548: .Xr printf 1
1.17 jmc 549: format
550: .Fa fmt .
1.7 aaron 551: .It Fn sub r t s
1.16 jmc 552: Substitutes
1.7 aaron 553: .Fa t
1.1 tholo 554: for the first occurrence of the regular expression
1.7 aaron 555: .Fa r
1.1 tholo 556: in the string
1.7 aaron 557: .Fa s .
1.1 tholo 558: If
1.7 aaron 559: .Fa s
1.1 tholo 560: is not given,
1.7 aaron 561: .Va $0
1.1 tholo 562: is used.
1.17 jmc 563: An ampersand
564: .Pq Sq &
565: in
566: .Fa t
567: is replaced in string
568: .Fa s
569: with regular expression
570: .Fa r .
571: A literal ampersand can be specified by preceding it with two backslashes
572: .Pq Sq \e\e .
573: A literal backslash can be specified by preceding it with another backslash
574: .Pq Sq \e\e .
1.7 aaron 575: .Fn sub
1.17 jmc 576: returns the number of replacements.
577: .It Fn substr s m n
578: Return at most the
579: .Fa n Ns -character
580: substring of
581: .Fa s
582: that begins at position
583: .Fa m
584: counted from 1.
585: If
586: .Fa n
587: is omitted, or if
588: .Fa n
589: specifies more characters than are left in the string,
590: the length of the substring is limited by the length of
591: .Fa s .
1.7 aaron 592: .It Fn tolower str
1.16 jmc 593: Returns a copy of
1.7 aaron 594: .Fa str
1.1 tholo 595: with all upper-case characters translated to their
596: corresponding lower-case equivalents.
1.7 aaron 597: .It Fn toupper str
1.16 jmc 598: Returns a copy of
1.7 aaron 599: .Fa str
1.1 tholo 600: with all lower-case characters translated to their
601: corresponding upper-case equivalents.
1.7 aaron 602: .El
1.17 jmc 603: .Ss Input/Output and General Functions
604: .Bl -tag -width "getline [var] < file"
605: .It Fn close expr
606: Closes the file or pipe
607: .Fa expr .
608: .Fa expr
609: should match the string that was used to open the file or pipe.
610: .It Ar cmd | Ic getline Op Va var
611: Read a record of input from a stream piped from the output of
612: .Ar cmd .
613: If
614: .Va var
615: is omitted, the variables
616: .Va $0
617: and
618: .Va NF
619: are set.
620: Otherwise
621: .Va var
622: is set.
623: If the stream is not open, it is opened.
624: As long as the stream remains open, subsequent calls
625: will read subsequent records from the stream.
626: The stream remains open until explicitly closed with a call to
627: .Fn close .
1.24 jmc 628: .Ic getline
629: returns 1 for a successful input, 0 for end of file, and \-1 for an error.
630: .It Fn fflush [expr]
1.39 jmc 631: Flushes any buffered output for the file or pipe
1.24 jmc 632: .Fa expr ,
633: or all open files or pipes if
634: .Fa expr
635: is omitted.
1.17 jmc 636: .Fa expr
637: should match the string that was used to open the file or pipe.
638: .It Ic getline
639: Sets
640: .Va $0
641: to the next input record from the current input file.
642: This form of
643: .Ic getline
644: sets the variables
645: .Va NF ,
646: .Va NR ,
647: and
648: .Va FNR .
1.7 aaron 649: .Ic getline
1.17 jmc 650: returns 1 for a successful input, 0 for end of file, and \-1 for an error.
651: .It Ic getline Va var
652: Sets
1.7 aaron 653: .Va $0
1.17 jmc 654: to variable
655: .Va var .
656: This form of
657: .Ic getline
658: sets the variables
659: .Va NR
660: and
661: .Va FNR .
662: .Ic getline
663: returns 1 for a successful input, 0 for end of file, and \-1 for an error.
664: .It Xo
665: .Ic getline Op Va var
666: .Pf \ \&< Ar file
667: .Xc
668: Sets
1.7 aaron 669: .Va $0
1.1 tholo 670: to the next record from
1.7 aaron 671: .Ar file .
1.17 jmc 672: If
673: .Va var
674: is omitted, the variables
675: .Va $0
676: and
677: .Va NF
678: are set.
679: Otherwise
680: .Va var
681: is set.
682: If
683: .Ar file
684: is not open, it is opened.
685: As long as the stream remains open, subsequent calls will read subsequent
686: records from
687: .Ar file .
688: .Ar file
689: remains open until explicitly closed with a call to
690: .Fn close .
691: .It Fn system cmd
692: Executes
693: .Fa cmd
694: and returns its exit status.
695: .El
1.30 jmc 696: .Ss Bit-Operation Functions
1.29 pyr 697: .Bl -tag -width "lshift(a, b)"
698: .It Fn compl x
699: Returns the bitwise complement of integer argument x.
700: .It Fn and x y
1.30 jmc 701: Performs a bitwise AND on integer arguments x and y.
1.29 pyr 702: .It Fn or x y
1.30 jmc 703: Performs a bitwise OR on integer arguments x and y.
1.29 pyr 704: .It Fn xor x y
1.30 jmc 705: Performs a bitwise Exclusive-OR on integer arguments x and y.
1.29 pyr 706: .It Fn lshift x n
1.39 jmc 707: Returns integer argument x shifted by n bits to the left.
1.29 pyr 708: .It Fn rshift x n
1.39 jmc 709: Returns integer argument x shifted by n bits to the right.
1.29 pyr 710: .El
1.37 jmc 711: .Sh EXIT STATUS
712: .Ex -std awk
713: .Pp
714: But note that the
715: .Ic exit
716: expression can modify the exit status.
1.7 aaron 717: .Sh EXAMPLES
1.16 jmc 718: Print lines longer than 72 characters:
719: .Pp
1.7 aaron 720: .Dl length($0) > 72
1.16 jmc 721: .Pp
722: Print first two fields in opposite order:
1.7 aaron 723: .Pp
724: .Dl { print $2, $1 }
1.16 jmc 725: .Pp
726: Same, with input fields separated by comma and/or blanks and tabs:
1.7 aaron 727: .Bd -literal -offset indent
1.1 tholo 728: BEGIN { FS = ",[ \et]*|[ \et]+" }
729: { print $2, $1 }
1.7 aaron 730: .Ed
1.16 jmc 731: .Pp
732: Add up first column, print sum and average:
1.7 aaron 733: .Bd -literal -offset indent
734: { s += $1 }
735: END { print "sum is", s, " average is", s/NR }
736: .Ed
1.16 jmc 737: .Pp
738: Print all lines between start/stop pairs:
1.7 aaron 739: .Pp
740: .Dl /start/, /stop/
1.16 jmc 741: .Pp
742: Simulate echo(1):
1.7 aaron 743: .Bd -literal -offset indent
744: BEGIN { # Simulate echo(1)
745: for (i = 1; i < ARGC; i++) printf "%s ", ARGV[i]
746: printf "\en"
747: exit }
1.19 jmc 748: .Ed
749: .Pp
750: Print an error message to standard error:
751: .Bd -literal -offset indent
752: { print "error!" > "/dev/stderr" }
1.7 aaron 753: .Ed
754: .Sh SEE ALSO
755: .Xr lex 1 ,
1.20 jmc 756: .Xr printf 1 ,
1.16 jmc 757: .Xr sed 1 ,
1.23 jmc 758: .Xr re_format 7 ,
759: .Xr script 7
1.7 aaron 760: .Rs
761: .%A A. V. Aho
762: .%A B. W. Kernighan
763: .%A P. J. Weinberger
764: .%T The AWK Programming Language
765: .%I Addison-Wesley
766: .%D 1988
767: .%O ISBN 0-201-07981-X
768: .Re
1.26 jmc 769: .Sh STANDARDS
770: The
771: .Nm
772: utility is compliant with the
1.33 jmc 773: .St -p1003.1-2008
1.26 jmc 774: specification.
775: .Pp
776: The flags
777: .Op Fl \&dV
778: and
779: .Op Fl safe ,
1.30 jmc 780: as well as the commands
781: .Cm fflush , compl , and , or ,
782: .Cm xor , lshift , rshift ,
1.26 jmc 783: are extensions to that specification.
1.32 jmc 784: .Pp
785: .Nm
786: does not support {n,m} pattern matching.
1.8 aaron 787: .Sh HISTORY
1.13 millert 788: An
1.8 aaron 789: .Nm
1.13 millert 790: utility appeared in
791: .At v7 .
1.7 aaron 792: .Sh BUGS
1.1 tholo 793: There are no explicit conversions between numbers and strings.
794: To force an expression to be treated as a number add 0 to it;
795: to force it to be treated as a string concatenate
1.7 aaron 796: .Li \&""
797: to it.
798: .Pp
1.1 tholo 799: The scope rules for variables in functions are a botch;
800: the syntax is worse.
![[BACK]](/icons/back.gif){kind=icon}
Return to awk.1 CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / awk