diff options
Diffstat (limited to 'gawk.1')
| -rw-r--r-- | gawk.1 | 234 |
1 files changed, 178 insertions, 56 deletions
@@ -1,4 +1,4 @@ -.TH GAWK 1 "Free Software Foundation" +.TH GAWK 1 "August 24 1989" "Free Software Foundation" .SH NAME gawk \- pattern scanning and processing language .SH SYNOPSIS @@ -8,21 +8,27 @@ gawk \- pattern scanning and processing language .B \-d ] [ .B \-D -] [ -.B \-v -] [ -.B \-V ] .. [ +.B \-a +] [ +.B \-e +] [ +.B \-c +] [ +.B \-C +] [ +.B \-V +] [ .BI \-F\^ fs +] [ +.B \-v +.IR var = val ] .B \-f .I program-file [ -.B \-f -.I program-file -\&.\^.\^. ] [ .B \-\^\- ] file .\^.\^. .br @@ -32,15 +38,24 @@ gawk \- pattern scanning and processing language .B \-d ] [ .B \-D -] [ -.B \-v -] [ -.B \-V ] .. [ +.B \-a +] [ +.B \-e +] [ +.B \-c +] [ +.B \-C +] [ +.B \-V +] [ .BI \-F\^ fs ] [ +.B \-v +.IR var = val +] [ .B \-\^\- ] .I program-text @@ -53,7 +68,8 @@ It conforms to the definition and description of the language in by Aho, Kernighan, and Weinberger, with the additional features defined in the System V Release 4 version of \s-1UNIX\s+1 -.IR awk . +.IR awk , +and some GNU-specific extensions. .PP The command line consists of options to .I gawk @@ -66,9 +82,9 @@ and .B ARGV pre-defined AWK variables. .PP -The options that -.I gawk -accepts are: +.I Gawk +accepts the following options, which should be available on any implementation +of the AWK language. .TP .BI \-F fs Use @@ -78,10 +94,23 @@ for the input field separator (the value of the predefined variable). .TP +\fB\-v\fI var\fR\^=\^\fIval\fR +Assign the value +.IR val , +to the variable +.IR var , +before execution of the program begins. +Such variable values are available to the +.B BEGIN +block of an AWK program. +.TP .BI \-f " program-file" Read the AWK program source from the file .IR program-file , instead of from the first command line argument. +Multiple +.B \-f +options may be used. .TP .B \-\^\- Signal the end of options. This is useful to allow further arguments to the @@ -89,10 +118,52 @@ AWK program itself to start with a ``\-''. This is mainly for consistency with the argument parsing convention used by most other System V programs. .PP +The following options are specific to the GNU implementation. +.TP +.B \-a +Use AWK style regular expressions as described in the book. +This is the current default, but may not be when the POSIX P1003.2 +standard is finalized. +It is orthogonal to +.BR \-c . +.TP +.B \-e +Use +.IR egrep (1) +style regular expressions as described in POSIX standard. +This may become the default when the POSIX P1003.2 +standard is finalized. +It is orthogonal to +.BR \-c . +.TP +.B \-c +Run in +.I compatibility +mode. In compatibility mode, +.I gawk +behaves identically to \s-1UNIX\s+1 +.IR awk ; +none of the GNU-specific extensions are recognized. +.TP +.B \-C +Print the short version of the GNU copyright information message on +the error output. +This option may disappear in a future version of +.IR gawk . +.TP +.B \-V +Print version information for this particular copy of +.I gawk +on the error output. +This is useful mainly for knowing if the current copy of +.I gawk +on your system +is up to date with respect to whatever the Free Software Foundation +is distributing. +This option may disappear in a future version of +.IR gawk . +.PP Any other options are flagged as illegal, but are otherwise ignored. -(However, see the -.B "GNU EXTENSIONS" -section, below.) .PP An AWK program consists of a sequence of pattern-action statements and optional function definitions. @@ -137,6 +208,9 @@ option contains a ``/'' character, no path search is performed. .PP .I Gawk compiles the program into an internal form, +executes the code in the +.B BEGIN +block(s) (if any), and then proceeds to read each file named in the .B ARGV @@ -167,10 +241,11 @@ is executed. .SH VARIABLES AND FIELDS AWK variables are dynamic; they come into existence when they are first used. Their values are either floating-point numbers or strings, -depending upon how they are used. AWK also has single dimension +depending upon how they are used. AWK also has one dimension arrays; multiply dimensioned arrays may be simulated. There are several pre-defined variables that AWK sets as a program runs; these will be described as needed and summarized below. +.SS Fields .PP As each input line is read, .I gawk @@ -258,6 +333,8 @@ Changing this array does not affect the environment seen by programs which spawns via redirection or the .B system function. +(This may change in a future version of +.IR gawk .) .TP \l'\fBIGNORECASE\fR' .B FILENAME the name of the current input file. @@ -284,6 +361,7 @@ and .BR !~ , and the .BR gsub() , +.BR index() , .BR match() , .BR split() , and @@ -363,7 +441,7 @@ arrays. For example: .ft B i = "A" ;\^ j = "B" ;\^ k = "C" .br -x[i,j,k] = "hello, world\en" +x[i, j, k] = "hello, world\en" .ft R .RE .PP @@ -596,6 +674,8 @@ matches zero or one grouping: matches .IR r . .RE +The escape sequences that are valid in string constants (see below) +are also legal in regular expressions. .SS Actions Action statements are enclosed in braces, .B { @@ -605,6 +685,7 @@ Action statements consist of the usual assignment, conditional, and looping statements found in most languages. The operators, control statements, and input/output statements available are patterned after those in C. +.SS Operators .PP The operators in AWK, in order of increasing precedence, are .PP @@ -664,6 +745,7 @@ increment and decrement, both prefix and postfix. .B $ field reference. .RE +.SS Control Statements .PP The control statements are as follows: @@ -682,6 +764,7 @@ as follows: \fB{ \fIstatements \fB} .fi .RE +.SS "I/O Statements" .PP The input/output statements are as follows: .PP @@ -767,6 +850,7 @@ pipes into .BR getline . .BR Getline will return 0 on end of file, and \-1 on an error. +.SS The \fIprintf\fP Statement .PP The AWK versions of the .B printf @@ -787,6 +871,10 @@ character of that string is printed. .B %d A decimal number (the integer part). .TP +.B %i +Just like +.BR %d . +.TP .B %e A floating point number of the form .BR [\-]d.ddddddE[+\^\-]dd . @@ -811,6 +899,14 @@ A character string. .B %x An unsigned hexadecimal number (an integer). .TP +.B %X +Like +.BR %x , +but using +.B ABCDEF +instead of +.BR abcdef . +.TP .B %% A single .B % @@ -845,6 +941,7 @@ routines are not supported. However, they may be simulated by using the AWK concatenation operation to build up a format specification dynamically. +.SS Special File Names .PP When doing I/O redirection from either .B print @@ -892,6 +989,7 @@ print "You blew it!" | "cat 1>&2" .RE .PP These file names may also be used on the command line to name data files. +.SS Numeric Functions .PP AWK has the following pre-defined arithmetic functions: .PP @@ -932,6 +1030,7 @@ is provided, the time of day will be used. The return value is the previous seed for the random number generator. .RE +.SS String Functions .PP AWK has the following pre-defined string functions: .PP @@ -1029,6 +1128,7 @@ with all the lower-case characters in translated to their corresponding upper-case counterparts. Non-alphabetic characters are left unchanged. .RE +.SS String Constants .PP String constants in AWK are sequences of characters enclosed between double quotes (\fB"\fR). Within strings, certain @@ -1152,10 +1252,16 @@ Concatenate and line number (a variation on a theme): .ft B { print NR, $0 } .ft R +.fi .SH SEE ALSO +.IR egrep (1) +.PP .IR "The AWK Programming Language" , Alfred V. Aho, Brian W. Kernighan, Peter J. Weinberger, Addison-Wesley, 1988. ISBN 0-201-07981-X. +.PP +.IR "The GAWK Manual" , +published by the Free Software Foundation, 1989. .SH SYSTEM V RELEASE 4 COMPATIBILITY A primary goal for .I gawk @@ -1169,6 +1275,24 @@ but are part of .I awk in System V Release 4. .PP +The +.B \-v +option for assigning variables before program execution starts is new. +The book indicates that command line variable assignment happens when +.I awk +would otherwise open the argument as a file, which is after the +.B BEGIN +block is executed. However, in earlier implementations, when such an +assignment appeared before any file names, the assignment would happen +.I before +the +.B BEGIN +block was run. Applications came to depend on this ``feature.'' +When +.I awk +was changed to match its documentation, this option was added to +accomodate applications that depended upon the old behaviour. +.PP When processing arguments, .I gawk uses the special option ``\fB\-\^\-\fP'' to signal the end of @@ -1185,11 +1309,22 @@ in .I gawk also returns its current seed. .PP +Other new features are: The use of multiple .B \-f -options is a new feature, as is the +options; the .B ENVIRON -array. +array; the +.BR \ea , +and +.BR \ev , +.B \ex +escape sequences; the +.B tolower +and +.B toupper +built-in functions; and the ANSI C conversion specifications in +.BR printf . .SH GNU EXTENSIONS .I Gawk has some extensions to System V @@ -1201,8 +1336,9 @@ with .BR \-DSTRICT , or by invoking .I gawk -with the name -.IR awk . +with the +.B \-c +option. If the underlying operating system supports the .B /dev/fd directory and corresponding files, then @@ -1219,25 +1355,10 @@ System V .RS .TP \l'\(bu' \(bu -The -.BR \ea , -.BR \ev , -or -.B \ex -escape sequences are not recognized. -.TP \l'\(bu' -\(bu The special file names available for I/O redirection are not recognized. .TP \l'\(bu' \(bu The -.B tolower -and -.B toupper -built-in string functions are not available. -.TP \l'\(bu' -\(bu -The .B IGNORECASE variable and its side-effects are not available. .TP \l'\(bu' @@ -1247,6 +1368,16 @@ No path search is performed for files named via the option. Therefore the .B AWKPATH environment variable is not special. +.TP \l'\(bu' +\(bu +The +.BR \-a , +.BR \-e , +.BR \-c , +.BR \-C , +and +.B \-V +command line options. .RE .PP The AWK book does not define the return value of the @@ -1262,8 +1393,9 @@ when closing a file or pipe, respectively. .PP When .I gawk -is invoked as -.IR awk , +is invoked with the +.B \-c +option, if the .I fs argument to the @@ -1272,6 +1404,7 @@ option is ``t'', then .B FS will be set to the tab character. Since this is a rather ugly special case, it is not the default behavior. +.ig .PP The rest of the features described in this section may change at some time in the future, or may go away entirely. @@ -1279,7 +1412,6 @@ You should not write programs that depend upon them. .PP .I Gawk accepts the following additional options: -.ig .TP .B \-D Turn on general debugging and turn on @@ -1301,24 +1433,14 @@ This option should only be of interest to the maintainers, and may not even be compiled into .IR gawk . .. -.TP -.B \-v -Print version information for this particular copy of -.I gawk -on the error output. -This is useful mainly for knowing if the current copy of -.I gawk -on your system -is up to date with respect to whatever the Free Software Foundation -is distributing. -.TP -.B \-V -Print the GNU copyright information message on the error output. .SH BUGS The .B \-F option is not necessary given the command line variable assignment feature; it remains only for backwards compatibility. +.PP +There are now too many options. +Fortunately, most of them are rarely needed. .SH AUTHORS The original version of \s-1UNIX\s+1 .I awk |