awk.1 (2010 09)

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awk(1) awk(1)

NAME

awk - pattern-directed scanning and processing language

SYNOPSIS

awk [-Ffs ][-v var

=value ][program  -f progﬁle ... ] [ ﬁle ... ]

DESCRIPTION

awk scans each input ﬁle for lines that match any of a set of patterns speciﬁed literally in program or in

one or more ﬁles speciﬁed as

-f progﬁle . With each pattern there can be an associated action that is to

be performed when a line in a ﬁle matches the pattern. Each line is matched against the pattern portion

of every pattern-action statement, and the associated action is performed for each matched pattern. The

ﬁle name

- means the standard input. Any ﬁle of the form var

=value is treated as an assignment, not a

ﬁlename. An assignment is evaluated at the time it would have been opened if it were a ﬁlename, unless

the

-v option is used.

An input line is made up of ﬁelds separated by white space, or by regular expression

FS. The ﬁelds are

denoted

$1, $2, ...; $0

refers to the entire line.

Options

awk recognizes the following options and arguments:

-F fs Specify regular expression used to separate ﬁelds. The default is to recognize space

and tab characters, and to discard leading spaces and tabs. If the -F option is

used, leading input ﬁeld separators are no longer discarded.

-f progfile Specify an awk program ﬁle. Up to 100 program ﬁles can be speciﬁed. The

pattern-action statements in these ﬁles are executed in the same order as the ﬁles

were speciﬁed.

-v var =value Cause var=value assignment to occur before the BEGIN action (if it exists) is exe-

cuted.

Statements

A pattern-action statement has the form:

pattern { action }

A missing { action } means print the line; a missing pattern always matches. Pattern-action statements

are separated by new-lines or semicolons.

An action is a sequence of statements. A statement can be one of the following:

if( expression ) statement [ else statement ]

while( expression) statement

for( expression ; expression ; expression) statement

for( var in array ) statement

do statement while( expression )

break

continue

{ [ statement ... ] }

expression # commonly var = expression

print [ expression-list ][> expression ]

printf format [, expression-list ][> expression ]

return [ expression ]

next # skip remaining patterns on this input line.

delete array [ expression ] # delete an array element.

exit [ expression ] # exit immediately; status is expression.

Statements are terminated by semicolons, newlines or right braces. An empty expression-list stands for

$0. String constants are quoted (""), with the usual C escapes recognized within. Expressions take on

string or numeric values as appropriate, and are built using the operators +, -, *, /, %, ˆ (exponentia-

tion), and concatenation (indicated by a blank). The operators ++, --, +=, -=, *=, /=, %=, ˆ=, **=, >,

>=, <, <=, ==, !=, "" (double quotes, string conversion operator), and ?: are also available in expres-

sions. Variables can be scalars, array elements (denoted x[i]) or ﬁelds. Variables are initialized to the

null string. Array subscripts can be any string, not necessarily numeric (this allows for a form of associa-

tive memory). Multiple subscripts such as [ i,j,k ] are permitted. The constituents are concatenated,

separated by the value of SUBSEP.

HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1

Summary of content (6 pages)

PAGE 1
awk(1) awk(1) NAME awk - pattern-directed scanning and processing language SYNOPSIS awk [-Ffs ] [-v var =value ] [ program  -f progfile ... ] [ file ... ] DESCRIPTION awk scans each input file for lines that match any of a set of patterns specified literally in program or in one or more files specified as -f progfile . With each pattern there can be an associated action that is to be performed when a line in a file matches the pattern.
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awk(1) awk(1) The print statement prints its arguments on the standard output (or on a file if >file or >>file is present or on a pipe if |cmd is present), separated by the current output field separator, and terminated by the output record separator. file and cmd can be literal names or parenthesized expressions. Identical string values in different statements denote the same open file. The printf statement formats its expression list according to the format (see printf (3S)).
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awk(1) awk(1) A pattern can consist of two patterns separated by a comma; in this case, the action is performed for all lines from an occurrence of the first pattern though an occurrence of the second. A relational expression is one of the following: expression matchop regular-expression expression relop expression expression in array-name (expr,expr,... ) in array-name where a relop is any of the six relational operators in C, and a matchop is either ˜ (matches) or !˜ (does not match).
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awk(1) awk(1) The arguments in ARGV can be modified or added to; ARGC can be altered. As each input file ends, awk will treat the next non-null element of ARGV, up to the current value of ARGC-1, inclusive, as the name of the next input file. Thus, setting an element of ARGV to null means that it will not be treated as an input file. The name - indicates the standard input.
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awk(1) awk(1) International Code Set Support Single- and multi-byte character code sets are supported except that variable names must contain only ASCII characters and regular expressions must contain only valid characters. DIAGNOSTICS awk supports up to 199 fields ($1, $2, ..., $199) per record.
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(Notes) A (Notes) aA 6 Hewlett-Packard Company −1− HP-UX 11i Version 3: September 2010