.ds PX \s-1POSIX\s+1

.ds UX \s-1UNIX\s+1

.ds AN \s-1ANSI\s+1

.TH GAWK 1 "May 28 1991" "Free Software Foundation" "Utility Commands"

.SH NAME

gawk \- pattern scanning and processing language

.SH SYNOPSIS

.B gawk

[

.B \-W

.I gawk-options

] [

.BI \-F\^ fs

] [

.B \-v

.IR var = val

]

.B \-f

.I program-file

[

.B \-\^\-

] file .\^.\^.

.br

.B gawk

[

.B \-W

.I gawk-options

] [

.BI \-F\^ fs

] [

.B \-v

.IR var = val

] [

.B \-\^\-

]

.I program-text

file .\^.\^.

.SH DESCRIPTION

.I Gawk

is the GNU Project's implementation of the AWK programming language.

It conforms to the definition of the language in

the \*(PX 1003.2 Command Language And Utilities Standard

(draft 11).

This version in turn is based on the description in

.IR "The AWK Programming Language" ,

by Aho, Kernighan, and Weinberger,

with the additional features defined in the System V Release 4 version

of \*(UX

.IR awk .

.I Gawk

also provides some GNU-specific extensions.

.PP

The command line consists of options to

.I gawk

itself, the AWK program text (if not supplied via the

.B \-f

option), and values to be made

available in the

.B ARGC

and

.B ARGV

pre-defined AWK variables.

.SH OPTIONS

.PP

.I Gawk

accepts the following options, which should be available on any implementation

of the AWK language.

.TP

.BI \-F fs

Use

.I fs

for the input field separator (the value of the

.B FS

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

AWK program itself to start with a ``\-''.

This is mainly for consistency with the argument parsing convention used

by most other \*(PX programs.

.PP

Following the \*(PX standard,

.IR gawk -specific

options are supplied via arguments to the

.B \-W

option.  Multiple

.B \-W

options may be supplied, or multiple arguments may be supplied together

if they are separated by commas, or enclosed in quotes and separated

by white space.

Case is ignored in arguments to the

.B \-W

option.

.PP

The

.B \-W

option accepts the following arguments:

.TP \w'\fBcopyright\fR'u+1n

.B compat

Run in

.I compatibility

mode.  In compatibility mode,

.I gawk

behaves identically to \*(UX

.IR awk ;

none of the GNU-specific extensions are recognized.

.TP

.PD 0

.B copyleft

.TP

.PD

.B copyright

Print the short version of the GNU copyright information message on

the error output.

.TP

.B lint

Provide warnings about constructs that are

dubious or non-portable to other AWK implementations.

.TP

.B posix

This turns on

.I compatibility 

mode, with the following additional restrictions:

.RS

.TP \w'\(bu'u+1n

\(bu

.B \ex

escape sequences are not recognized.

.TP

\(bu

The synonym

.B func

for the keyword

.B function

is not recognized.

.TP

\(bu

The operators

.B **

and

.B **=

cannot be used in place of

.B ^

and

.BR ^= .

.RE

.TP

.B version

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.

.PP

Any other options are flagged as illegal, but are otherwise ignored.

.SH AWK PROGRAM EXECUTION

.PP

An AWK program consists of a sequence of pattern-action statements

and optional function definitions.

.RS

.PP

\fIpattern\fB	{ \fIaction statements\fB }\fR

.br

\fBfunction \fIname\fB(\fIparameter list\fB) { \fIstatements\fB }\fR

.RE

.PP

.I Gawk

first reads the program source from the

.IR program-file (s)

if specified, or from the first non-option argument on the command line.

The

.B \-f

option may be used multiple times on the command line.

.I Gawk

will read the program text as if all the

.IR program-file s

had been concatenated together.  This is useful for building libraries

of AWK functions, without having to include them in each new AWK