Annotation of src/usr.bin/awk/awk.1, Revision 1.28
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1.27 jmc 26: .Dd $Mdocdate$
1.7 aaron 27: .Dt AWK 1
28: .Os
29: .Sh NAME
30: .Nm awk
31: .Nd pattern-directed scanning and processing language
32: .Sh SYNOPSIS
33: .Nm awk
1.16 jmc 34: .Op Fl safe
35: .Op Fl V
36: .Op Fl d Ns Op Ar n
1.7 aaron 37: .Op Fl F Ar fs
1.16 jmc 38: .Oo Fl v Ar var Ns =
39: .Ns Ar value Oc
1.18 jmc 40: .Op Ar prog | Fl f Ar progfile
1.7 aaron 41: .Ar
42: .Nm nawk
43: .Ar ...
44: .Sh DESCRIPTION
45: .Nm
1.1 tholo 46: scans each input
1.7 aaron 47: .Ar file
1.1 tholo 48: for lines that match any of a set of patterns specified literally in
1.7 aaron 49: .Ar prog
1.16 jmc 50: or in one or more files specified as
1.7 aaron 51: .Fl f Ar progfile .
1.16 jmc 52: With each pattern there can be an associated action that will be performed
1.1 tholo 53: when a line of a
1.7 aaron 54: .Ar file
1.1 tholo 55: matches the pattern.
56: Each line is matched against the
57: pattern portion of every pattern-action statement;
58: the associated action is performed for each matched pattern.
1.6 aaron 59: The file name
1.16 jmc 60: .Sq -
1.1 tholo 61: means the standard input.
62: Any
1.7 aaron 63: .Ar file
1.1 tholo 64: of the form
1.16 jmc 65: .Ar var Ns = Ns Ar value
1.1 tholo 66: is treated as an assignment, not a filename,
67: and is executed at the time it would have been opened if it were a filename.
1.16 jmc 68: .Pp
69: The options are as follows:
1.20 jmc 70: .Bl -tag -width "-safe "
1.16 jmc 71: .It Fl d Ns Op Ar n
72: Debug mode.
73: Set debug level to
74: .Ar n ,
75: or 1 if
76: .Ar n
77: is not specified.
78: A value greater than 1 causes
79: .Nm
80: to dump core on fatal errors.
81: .It Fl F Ar fs
82: Define the input field separator to be the regular expression
1.7 aaron 83: .Ar fs .
1.25 jmc 84: .It Fl f Ar progfile
1.16 jmc 85: Read program code from the specified file
1.25 jmc 86: .Ar progfile
1.16 jmc 87: instead of from the command line.
88: .It Fl safe
89: Disable file output
1.17 jmc 90: .Pf ( Ic print No > ,
91: .Ic print No >> ) ,
1.7 aaron 92: process creation
93: .Po
1.17 jmc 94: .Ar cmd | Ic getline ,
95: .Ic print No \&| ,
96: .Ic system
1.7 aaron 97: .Pc
98: and access to the environment
1.17 jmc 99: .Pf ( Va ENVIRON ;
1.18 jmc 100: see the section on variables below).
1.17 jmc 101: This is a first
1.16 jmc 102: .Pq and not very reliable
103: approximation to a
1.7 aaron 104: .Dq safe
105: version of
1.16 jmc 106: .Nm .
107: .It Fl V
108: Print the version number of
109: .Nm
110: to standard output and exit.
111: .It Fl v Ar var Ns = Ns Ar value
112: Assign
113: .Ar value
114: to variable
115: .Ar var
116: before
117: .Ar prog
118: is executed;
119: any number of
120: .Fl v
121: options may be present.
122: .El
1.7 aaron 123: .Pp
1.18 jmc 124: The input is normally made up of input lines
125: .Pq records
126: separated by newlines, or by the value of
127: .Va RS .
128: If
129: .Va RS
130: is null, then any number of blank lines are used as the record separator,
131: and newlines are used as field separators
132: (in addition to the value of
133: .Va FS ) .
134: This is convenient when working with multi-line records.
135: .Pp
1.7 aaron 136: An input line is normally made up of fields separated by whitespace,
1.18 jmc 137: or by the regular expression
1.7 aaron 138: .Va FS .
1.1 tholo 139: The fields are denoted
1.7 aaron 140: .Va $1 , $2 , ... ,
141: while
142: .Va $0
1.1 tholo 143: refers to the entire line.
144: If
1.7 aaron 145: .Va FS
1.1 tholo 146: is null, the input line is split into one field per character.
1.7 aaron 147: .Pp
1.18 jmc 148: Normally, any number of blanks separate fields.
149: In order to set the field separator to a single blank, use the
150: .Fl F
151: option with a value of
152: .Sq [\ \&] .
153: If a field separator of
154: .Sq t
155: is specified,
156: .Nm
157: treats it as if
158: .Sq \et
159: had been specified and uses
160: .Aq TAB
161: as the field separator.
162: In order to use a literal
163: .Sq t
164: as the field separator, use the
165: .Fl F
166: option with a value of
167: .Sq [t] .
168: .Pp
1.1 tholo 169: A pattern-action statement has the form
1.7 aaron 170: .Pp
171: .D1 Ar pattern Ic \&{ Ar action Ic \&}
172: .Pp
1.6 aaron 173: A missing
1.7 aaron 174: .Ic \&{ Ar action Ic \&}
1.1 tholo 175: means print the line;
176: a missing pattern always matches.
177: Pattern-action statements are separated by newlines or semicolons.
1.7 aaron 178: .Pp
1.18 jmc 179: Newlines are permitted after a terminating statement or following a comma
180: .Pq Sq ,\& ,
181: an open brace
182: .Pq Sq { ,
183: a logical AND
184: .Pq Sq && ,
185: a logical OR
186: .Pq Sq || ,
187: after the
188: .Sq do
189: or
190: .Sq else
191: keywords,
192: or after the closing parenthesis of an
193: .Sq if ,
194: .Sq for ,
195: or
196: .Sq while
197: statement.
198: Additionally, a backslash
199: .Pq Sq \e
200: can be used to escape a newline between tokens.
201: .Pp
1.1 tholo 202: An action is a sequence of statements.
203: A statement can be one of the following:
1.7 aaron 204: .Bd -unfilled -offset indent
205: .Ic if ( Xo
206: .Ar expression ) statement \&
207: .Op Ic else Ar statement
208: .Xc
209: .Ic while ( Ar expression ) statement
210: .Ic for ( Xo
211: .Ar expression ; expression ; expression ) statement
212: .Xc
213: .Ic for ( Xo
214: .Ar var Ic in Ar array ) statement
215: .Xc
216: .Ic do Ar statement Ic while ( Ar expression )
217: .Ic break
218: .Ic continue
219: .Ic { Oo Ar statement ... Oc Ic \& }
220: .Ar expression Xo
221: .No "# commonly" \&
222: .Ar var Ic = Ar expression
223: .Xc
224: .Ic print Xo
225: .Op Ar expression-list
1.17 jmc 226: .Op > Ns Ar expression
1.7 aaron 227: .Xc
228: .Ic printf Ar format Xo
229: .Op Ar ... , expression-list
1.17 jmc 230: .Op > Ns Ar expression
1.7 aaron 231: .Xc
232: .Ic return Op Ar expression
233: .Ic next Xo
234: .No "# skip remaining patterns on this input line"
235: .Xc
236: .Ic nextfile Xo
237: .No "# skip rest of this file, open next, start at top"
238: .Xc
239: .Ic delete Ar array Ns Xo
240: .Ic \&[ Ns Ar expression Ns Ic \&]
241: .No \& "# delete an array element"
242: .Xc
243: .Ic delete Ar array Xo
244: .No "# delete all elements of array"
245: .Xc
246: .Ic exit Xo
247: .Op Ar expression
248: .No \& "# exit immediately; status is" Ar expression
249: .Xc
250: .Ed
251: .Pp
1.1 tholo 252: Statements are terminated by
253: semicolons, newlines or right braces.
254: An empty
1.7 aaron 255: .Ar expression-list
1.1 tholo 256: stands for
1.7 aaron 257: .Ar $0 .
258: String constants are quoted
259: .Li \&"" ,
1.20 jmc 260: with the usual C escapes recognized within
261: (see
262: .Xr printf 1
263: for a complete list of these).
1.1 tholo 264: Expressions take on string or numeric values as appropriate,
265: and are built using the operators
1.7 aaron 266: .Ic + \- * / % ^
1.20 jmc 267: .Pq exponentiation ,
268: and concatenation
269: .Pq indicated by whitespace .
1.1 tholo 270: The operators
1.16 jmc 271: .Ic \&! ++ \-\- += \-= *= /= %= ^=
272: .Ic > >= < <= == != ?:
1.1 tholo 273: are also available in expressions.
274: Variables may be scalars, array elements
275: (denoted
1.7 aaron 276: .Li x[i] )
1.1 tholo 277: or fields.
278: Variables are initialized to the null string.
279: Array subscripts may be any string,
280: not necessarily numeric;
281: this allows for a form of associative memory.
282: Multiple subscripts such as
1.7 aaron 283: .Li [i,j,k]
1.1 tholo 284: are permitted; the constituents are concatenated,
285: separated by the value of
1.17 jmc 286: .Va SUBSEP
1.18 jmc 287: .Pq see the section on variables below ) .
1.7 aaron 288: .Pp
1.1 tholo 289: The
1.7 aaron 290: .Ic print
1.1 tholo 291: statement prints its arguments on the standard output
292: (or on a file if
1.17 jmc 293: .Pf > Ns Ar file
1.1 tholo 294: or
1.17 jmc 295: .Pf >> Ns Ar file
1.1 tholo 296: is present or on a pipe if
1.17 jmc 297: .Pf |\ \& Ar cmd
1.1 tholo 298: is present), separated by the current output field separator,
299: and terminated by the output record separator.
1.7 aaron 300: .Ar file
1.1 tholo 301: and
1.7 aaron 302: .Ar cmd
1.1 tholo 303: may be literal names or parenthesized expressions;
304: identical string values in different statements denote
305: the same open file.
306: The
1.7 aaron 307: .Ic printf
1.1 tholo 308: statement formats its expression list according to the format
309: (see
1.28 ! jmc 310: .Xr printf 1 ) .
1.18 jmc 311: .Pp
312: Patterns are arbitrary Boolean combinations
313: (with
314: .Ic "\&! || &&" )
315: of regular expressions and
316: relational expressions.
1.22 jmc 317: .Nm
318: supports extended regular expressions
319: .Pq EREs .
320: See
321: .Xr re_format 7
322: for more information on regular expressions.
1.18 jmc 323: Isolated regular expressions
324: in a pattern apply to the entire line.
325: Regular expressions may also occur in
326: relational expressions, using the operators
327: .Ic ~
328: and
329: .Ic !~ .
330: .Pf / Ns Ar re Ns /
331: is a constant regular expression;
332: any string (constant or variable) may be used
333: as a regular expression, except in the position of an isolated regular expression
334: in a pattern.
335: .Pp
336: A pattern may consist of two patterns separated by a comma;
337: in this case, the action is performed for all lines
338: from an occurrence of the first pattern
339: through an occurrence of the second.
340: .Pp
341: A relational expression is one of the following:
342: .Bd -unfilled -offset indent
343: .Ar expression matchop regular-expression
344: .Ar expression relop expression
345: .Ar expression Ic in Ar array-name
346: .Ic \&( Ns Xo
347: .Ar expr , expr , \&... Ns Ic \&) in
348: .Ar \& array-name
349: .Xc
350: .Ed
351: .Pp
352: where a
353: .Ar relop
354: is any of the six relational operators in C, and a
355: .Ar matchop
356: is either
357: .Ic ~
358: (matches)
359: or
360: .Ic !~
361: (does not match).
362: A conditional is an arithmetic expression,
363: a relational expression,
364: or a Boolean combination
365: of these.
366: .Pp
367: The special patterns
368: .Ic BEGIN
369: and
370: .Ic END
371: may be used to capture control before the first input line is read
372: and after the last.
373: .Ic BEGIN
374: and
375: .Ic END
376: do not combine with other patterns.
377: .Pp
378: Variable names with special meanings:
379: .Pp
1.20 jmc 380: .Bl -tag -width "FILENAME " -compact
1.18 jmc 381: .It Va ARGC
382: Argument count, assignable.
383: .It Va ARGV
384: Argument array, assignable;
385: non-null members are taken as filenames.
386: .It Va CONVFMT
387: Conversion format when converting numbers
388: (default
389: .Qq Li %.6g ) .
390: .It Va ENVIRON
391: Array of environment variables; subscripts are names.
392: .It Va FILENAME
393: The name of the current input file.
394: .It Va FNR
395: Ordinal number of the current record in the current file.
396: .It Va FS
397: Regular expression used to separate fields; also settable
398: by option
399: .Fl F Ar fs .
400: .It Va NF
401: Number of fields in the current record.
402: .Va $NF
403: can be used to obtain the value of the last field in the current record.
404: .It Va NR
405: Ordinal number of the current record.
406: .It Va OFMT
407: Output format for numbers (default
408: .Qq Li %.6g ) .
409: .It Va OFS
410: Output field separator (default blank).
411: .It Va ORS
412: Output record separator (default newline).
413: .It Va RLENGTH
414: The length of the string matched by the
415: .Fn match
416: function.
417: .It Va RS
418: Input record separator (default newline).
419: .It Va RSTART
420: The starting position of the string matched by the
421: .Fn match
422: function.
423: .It Va SUBSEP
424: Separates multiple subscripts (default 034).
425: .El
1.17 jmc 426: .Sh FUNCTIONS
427: The awk language has a variety of built-in functions:
428: arithmetic, string, input/output and general.
429: .Ss Arithmetic Functions
430: .Bl -tag -width "atan2(y, x)"
431: .It Fn atan2 y x
432: Return the arctangent of
433: .Fa y Ns / Ns Fa x
434: in radians.
435: .It Fn cos x
436: Return the cosine of
437: .Fa x ,
438: where
439: .Fa x
440: is in radians.
441: .It Fn exp x
442: Return the exponential of
443: .Fa x .
444: .It Fn int x
445: Return
446: .Fa x
447: truncated to an integer value.
448: .It Fn log x
449: Return the natural logarithm of
450: .Fa x .
1.7 aaron 451: .It Fn rand
1.17 jmc 452: Return a random number,
453: .Fa n ,
454: such that
455: .Sm off
456: .Pf 0 \*(Le Fa n No \*(Lt 1 .
457: .Sm on
458: .It Fn sin x
459: Return the sine of
460: .Fa x ,
461: where
462: .Fa x
463: is in radians.
464: .It Fn sqrt x
465: Return the square root of
466: .Fa x .
467: .It Fn srand expr
1.16 jmc 468: Sets seed for
1.7 aaron 469: .Fn rand
1.17 jmc 470: to
471: .Fa expr
1.1 tholo 472: and returns the previous seed.
1.17 jmc 473: If
474: .Fa expr
475: is omitted, the time of day is used instead.
476: .El
477: .Ss String Functions
478: .Bl -tag -width "split(s, a, fs)"
479: .It Fn gsub r t s
480: The same as
481: .Fn sub
482: except that all occurrences of the regular expression are replaced.
483: .Fn gsub
484: returns the number of replacements.
1.7 aaron 485: .It Fn index s t
1.16 jmc 486: The position in
1.7 aaron 487: .Fa s
1.1 tholo 488: where the string
1.7 aaron 489: .Fa t
1.1 tholo 490: occurs, or 0 if it does not.
1.17 jmc 491: .It Fn length s
492: The length of
493: .Fa s
494: taken as a string,
495: or of
496: .Va $0
497: if no argument is given.
1.7 aaron 498: .It Fn match s r
1.16 jmc 499: The position in
1.7 aaron 500: .Fa s
1.1 tholo 501: where the regular expression
1.7 aaron 502: .Fa r
1.1 tholo 503: occurs, or 0 if it does not.
1.17 jmc 504: The variable
1.7 aaron 505: .Va RSTART
1.17 jmc 506: is set to the starting position of the matched string
507: .Pq which is the same as the returned value
508: or zero if no match is found.
509: The variable
1.7 aaron 510: .Va RLENGTH
1.17 jmc 511: is set to the length of the matched string,
512: or \-1 if no match is found.
1.7 aaron 513: .It Fn split s a fs
1.16 jmc 514: Splits the string
1.7 aaron 515: .Fa s
1.1 tholo 516: into array elements
1.7 aaron 517: .Va a[1] , a[2] , ... , a[n]
1.1 tholo 518: and returns
1.7 aaron 519: .Va n .
1.1 tholo 520: The separation is done with the regular expression
1.7 aaron 521: .Ar fs
1.1 tholo 522: or with the field separator
1.7 aaron 523: .Va FS
1.1 tholo 524: if
1.7 aaron 525: .Ar fs
1.1 tholo 526: is not given.
527: An empty string as field separator splits the string
528: into one array element per character.
1.17 jmc 529: .It Fn sprintf fmt expr ...
530: The string resulting from formatting
531: .Fa expr , ...
532: according to the
1.28 ! jmc 533: .Xr printf 1
1.17 jmc 534: format
535: .Fa fmt .
1.7 aaron 536: .It Fn sub r t s
1.16 jmc 537: Substitutes
1.7 aaron 538: .Fa t
1.1 tholo 539: for the first occurrence of the regular expression
1.7 aaron 540: .Fa r
1.1 tholo 541: in the string
1.7 aaron 542: .Fa s .
1.1 tholo 543: If
1.7 aaron 544: .Fa s
1.1 tholo 545: is not given,
1.7 aaron 546: .Va $0
1.1 tholo 547: is used.
1.17 jmc 548: An ampersand
549: .Pq Sq &
550: in
551: .Fa t
552: is replaced in string
553: .Fa s
554: with regular expression
555: .Fa r .
556: A literal ampersand can be specified by preceding it with two backslashes
557: .Pq Sq \e\e .
558: A literal backslash can be specified by preceding it with another backslash
559: .Pq Sq \e\e .
1.7 aaron 560: .Fn sub
1.17 jmc 561: returns the number of replacements.
562: .It Fn substr s m n
563: Return at most the
564: .Fa n Ns -character
565: substring of
566: .Fa s
567: that begins at position
568: .Fa m
569: counted from 1.
570: If
571: .Fa n
572: is omitted, or if
573: .Fa n
574: specifies more characters than are left in the string,
575: the length of the substring is limited by the length of
576: .Fa s .
1.7 aaron 577: .It Fn tolower str
1.16 jmc 578: Returns a copy of
1.7 aaron 579: .Fa str
1.1 tholo 580: with all upper-case characters translated to their
581: corresponding lower-case equivalents.
1.7 aaron 582: .It Fn toupper str
1.16 jmc 583: Returns a copy of
1.7 aaron 584: .Fa str
1.1 tholo 585: with all lower-case characters translated to their
586: corresponding upper-case equivalents.
1.7 aaron 587: .El
1.17 jmc 588: .Ss Input/Output and General Functions
589: .Bl -tag -width "getline [var] < file"
590: .It Fn close expr
591: Closes the file or pipe
592: .Fa expr .
593: .Fa expr
594: should match the string that was used to open the file or pipe.
595: .It Ar cmd | Ic getline Op Va var
596: Read a record of input from a stream piped from the output of
597: .Ar cmd .
598: If
599: .Va var
600: is omitted, the variables
601: .Va $0
602: and
603: .Va NF
604: are set.
605: Otherwise
606: .Va var
607: is set.
608: If the stream is not open, it is opened.
609: As long as the stream remains open, subsequent calls
610: will read subsequent records from the stream.
611: The stream remains open until explicitly closed with a call to
612: .Fn close .
1.24 jmc 613: .Ic getline
614: returns 1 for a successful input, 0 for end of file, and \-1 for an error.
615: .It Fn fflush [expr]
616: Flushes any buffered output for the file, pipe
617: .Fa expr ,
618: or all open files or pipes if
619: .Fa expr
620: is omitted.
1.17 jmc 621: .Fa expr
622: should match the string that was used to open the file or pipe.
623: .It Ic getline
624: Sets
625: .Va $0
626: to the next input record from the current input file.
627: This form of
628: .Ic getline
629: sets the variables
630: .Va NF ,
631: .Va NR ,
632: and
633: .Va FNR .
1.7 aaron 634: .Ic getline
1.17 jmc 635: returns 1 for a successful input, 0 for end of file, and \-1 for an error.
636: .It Ic getline Va var
637: Sets
1.7 aaron 638: .Va $0
1.17 jmc 639: to variable
640: .Va var .
641: This form of
642: .Ic getline
643: sets the variables
644: .Va NR
645: and
646: .Va FNR .
647: .Ic getline
648: returns 1 for a successful input, 0 for end of file, and \-1 for an error.
649: .It Xo
650: .Ic getline Op Va var
651: .Pf \ \&< Ar file
652: .Xc
653: Sets
1.7 aaron 654: .Va $0
1.1 tholo 655: to the next record from
1.7 aaron 656: .Ar file .
1.17 jmc 657: If
658: .Va var
659: is omitted, the variables
660: .Va $0
661: and
662: .Va NF
663: are set.
664: Otherwise
665: .Va var
666: is set.
667: If
668: .Ar file
669: is not open, it is opened.
670: As long as the stream remains open, subsequent calls will read subsequent
671: records from
672: .Ar file .
673: .Ar file
674: remains open until explicitly closed with a call to
675: .Fn close .
676: .It Fn system cmd
677: Executes
678: .Fa cmd
679: and returns its exit status.
680: .El
681: .Pp
682: Functions may be defined (at the position of a pattern-action statement)
683: thusly:
684: .Pp
685: .Dl function foo(a, b, c) { ...; return x }
1.7 aaron 686: .Pp
1.17 jmc 687: Parameters are passed by value if scalar, and by reference if array name;
688: functions may be called recursively.
689: Parameters are local to the function; all other variables are global.
690: Thus local variables may be created by providing excess parameters in
691: the function definition.
1.7 aaron 692: .Sh EXAMPLES
1.16 jmc 693: Print lines longer than 72 characters:
694: .Pp
1.7 aaron 695: .Dl length($0) > 72
1.16 jmc 696: .Pp
697: Print first two fields in opposite order:
1.7 aaron 698: .Pp
699: .Dl { print $2, $1 }
1.16 jmc 700: .Pp
701: Same, with input fields separated by comma and/or blanks and tabs:
1.7 aaron 702: .Bd -literal -offset indent
1.1 tholo 703: BEGIN { FS = ",[ \et]*|[ \et]+" }
704: { print $2, $1 }
1.7 aaron 705: .Ed
1.16 jmc 706: .Pp
707: Add up first column, print sum and average:
1.7 aaron 708: .Bd -literal -offset indent
709: { s += $1 }
710: END { print "sum is", s, " average is", s/NR }
711: .Ed
1.16 jmc 712: .Pp
713: Print all lines between start/stop pairs:
1.7 aaron 714: .Pp
715: .Dl /start/, /stop/
1.16 jmc 716: .Pp
717: Simulate echo(1):
1.7 aaron 718: .Bd -literal -offset indent
719: BEGIN { # Simulate echo(1)
720: for (i = 1; i < ARGC; i++) printf "%s ", ARGV[i]
721: printf "\en"
722: exit }
1.19 jmc 723: .Ed
724: .Pp
725: Print an error message to standard error:
726: .Bd -literal -offset indent
727: { print "error!" > "/dev/stderr" }
1.7 aaron 728: .Ed
729: .Sh SEE ALSO
730: .Xr lex 1 ,
1.20 jmc 731: .Xr printf 1 ,
1.16 jmc 732: .Xr sed 1 ,
1.23 jmc 733: .Xr re_format 7 ,
734: .Xr script 7
1.21 jmc 735: .Pp
736: "Awk \(em A Pattern Scanning and Processing Language",
737: .Pa /usr/share/doc/usd/16.awk/ .
1.7 aaron 738: .Rs
739: .%A A. V. Aho
740: .%A B. W. Kernighan
741: .%A P. J. Weinberger
742: .%T The AWK Programming Language
743: .%I Addison-Wesley
744: .%D 1988
745: .%O ISBN 0-201-07981-X
746: .Re
1.26 jmc 747: .Sh STANDARDS
748: The
749: .Nm
750: utility is compliant with the
751: .St -p1003.1-2004
752: specification.
753: .Pp
754: The flags
755: .Op Fl \&dV
756: and
757: .Op Fl safe ,
758: as well as the command
759: .Cm fflush ,
760: are extensions to that specification.
1.8 aaron 761: .Sh HISTORY
1.13 millert 762: An
1.8 aaron 763: .Nm
1.13 millert 764: utility appeared in
765: .At v7 .
1.7 aaron 766: .Sh BUGS
1.1 tholo 767: There are no explicit conversions between numbers and strings.
768: To force an expression to be treated as a number add 0 to it;
769: to force it to be treated as a string concatenate
1.7 aaron 770: .Li \&""
771: to it.
772: .Pp
1.1 tholo 773: The scope rules for variables in functions are a botch;
774: the syntax is worse.
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