src/usr.bin/awk/awk.1 - diff

Return to awk.1 CVS log

Up to [local] / src / usr.bin / awk

Diff for /src/usr.bin/awk/awk.1 between version 1.15 and 1.16

version 1.15, 2003/11/24 10:58:08

version 1.16, 2003/12/12 19:50:55

Line 31

.Nd pattern-directed scanning and processing language

.Sh SYNOPSIS

.Nm awk

.Op Fl F Ar fs

.Op Fl v Ar var=value

.Op Fl safe

.Op Fl mr Ar n

.Op Fl V

.Op Fl mf Ar n

.Op Fl d Ns Op Ar n

.Op Ar prog | Fl f Ar progfile

.Op Fl F Ar fs

.Oo Fl v Ar var Ns =

.Ns Ar value Oc

.Ar prog | Fl f Ar progfile

.Ar

.Nm nawk

.Ar ...

Line 46

Line 47

.Ar file

for lines that match any of a set of patterns specified literally in

.Ar prog

or in one or more files

or in one or more files specified as

specified as

.Fl f Ar progfile .

With each pattern

With each pattern there can be an associated action that will be performed

there can be an associated action that will be performed

when a line of a

.Ar file

matches the pattern.

Line 58

Line 57

pattern portion of every pattern-action statement;

the associated action is performed for each matched pattern.

The file name

.Sq Pa \-

.Sq -

means the standard input.

Any

.Ar file

of the form

.Ar var=value

.Ar var Ns = Ns Ar value

is treated as an assignment, not a filename,

and is executed at the time it would have been opened if it were a filename.

The option

.Pp

.Fl v

The options are as follows:

followed by

.Bl -tag -width Ds

.Ar var=value

.It Fl d Ns Op Ar n

is an assignment to be done before

Debug mode.

.Ar prog

Set debug level to

is executed;

.Ar n ,

any number of

or 1 if

.Fl v

.Ar n

options may be present.

is not specified.

The

A value greater than 1 causes

.Fl F Ar fs

.Nm

option defines the input field separator to be the regular expression

to dump core on fatal errors.

.It Fl F Ar fs

Define the input field separator to be the regular expression

.Ar fs .

The

.It Fl f Ar filename

.Fl safe

Read program code from the specified file

option disables file output

.Ar filename

.Po

instead of from the command line.

.Ic print Ic > ,

.It Fl safe

.Ic print Ic >> ,

Disable file output

.Pc

.Pf ( Ic print > ,

.Ic print >> ) ,

process creation

.Po

.Ar cmd Ic \&| getline ,

Line 95

Line 97

and access to the environment

.Pq Va ENVIRON .

This

is a first (and not very reliable) approximation to a

is a first

.Pq and not very reliable

approximation to a

.Dq safe

version of

.Nm awk .

.Nm .

.It Fl V

Print the version number of

.Nm

to standard output and exit.

.It Fl v Ar var Ns = Ns Ar value

Assign

.Ar value

to variable

.Ar var

before

.Ar prog

is executed;

any number of

.Fl v

options may be present.

.El

.Pp

An input line is normally made up of fields separated by whitespace,

or by regular expression

Line 112

Line 132

.Va FS

is null, the input line is split into one field per character.

.Pp

To compensate for inadequate implementation of storage management,

the

.Fl mr

option can be used to set the maximum size of the input record,

and the

.Fl mf

option to set the maximum number of fields.

.Pp

A pattern-action statement has the form

.Pp

.D1 Ar pattern Ic \&{ Ar action Ic \&}

Line 194

Line 206

.Ic + \- * / % ^

(exponentiation), and concatenation (indicated by whitespace).

The operators

.Ic \&! ++ \-\- += \-= *= /= %= ^= > >= < <= == != ?:

.Ic \&! ++ \-\- += \-= *= /= %= ^=

.Ic > >= < <= == != ?:

are also available in expressions.

Variables may be scalars, array elements

(denoted

Line 253

Line 266

Other built-in functions:

.Bl -tag -width Fn

.It Fn length

the length of its argument

The length of its argument

taken as a string,

or of

.Va $0

if no argument.

.It Fn rand

random number on (0,1)

Random number on (0,1).

.It Fn srand

sets seed for

Sets seed for

.Fn rand

and returns the previous seed.

.It Fn int

truncates to an integer value.

Truncates to an integer value.

.It Fn substr s m n

the

The

.Fa n Ns No -character

substring of

.Fa s

Line 275

Line 288

.Fa m

counted from 1.

.It Fn index s t

the position in

The position in

.Fa s

where the string

.Fa t

occurs, or 0 if it does not.

.It Fn match s r

the position in

The position in

.Fa s

where the regular expression

.Fa r

Line 292

Line 305

.Va RLENGTH

are set to the position and length of the matched string.

.It Fn split s a fs

splits the string

Splits the string

.Fa s

into array elements

.Va a[1] , a[2] , ... , a[n]

Line 308

Line 321

An empty string as field separator splits the string

into one array element per character.

.It Fn sub r t s

substitutes

Substitutes

.Fa t

for the first occurrence of the regular expression

.Fa r

Line 320

Line 333

.Va $0

is used.

.It Fn gsub r t s

same as

Same as

.Fn sub

except that all occurrences of the regular expression

are replaced;

Line 329

Line 342

.Fn gsub

return the number of replacements.

.It Fn sprintf fmt expr ...

the string resulting from formatting

The string resulting from formatting

.Fa expr , ...

according to the

.Xr printf 3

format

.Fa fmt .

.It Fn system cmd

executes

Executes

.Fa cmd

and returns its exit status.

.It Fn tolower str

returns a copy of

Returns a copy of

.Fa str

with all upper-case characters translated to their

corresponding lower-case equivalents.

.It Fn toupper str

returns a copy of

Returns a copy of

.Fa str

with all lower-case characters translated to their

corresponding upper-case equivalents.

Line 445

Line 458

.Pp

Variable names with special meanings:

.Pp

.Bl -tag -width Va -compact

.Bl -tag -width "FILENAME" -compact

.It Va ARGC

Argument count, assignable.

.It Va ARGV

Argument array, assignable;

non-null members are taken as filenames.

.It Va CONVFMT

conversion format used when converting numbers

Conversion format used when converting numbers

(default

.Qq Li %.6g )

.Qq Li %.6g ) .

.It Va ENVIRON

Array of environment variables; subscripts are names.

.It Va FILENAME

The name of the current input file.

.It Va FNR

Ordinal number of the current record in the current file.

.It Va FS

regular expression used to separate fields; also settable

Regular expression used to separate fields; also settable

by option

.Fl F Ar fs .

.It Va NF

number of fields in the current record

Number of fields in the current record.

.It Va NR

ordinal number of the current record

Ordinal number of the current record.

.It Va FNR

.It Va OFMT

ordinal number of the current record in the current file

Output format for numbers (default

.It Va FILENAME

.Qq Li %.6g ) .

the name of the current input file

.It Va RS

input record separator (default newline)

.It Va OFS

output field separator (default blank)

Output field separator (default blank).

.It Va ORS

output record separator (default newline)

Output record separator (default newline).

.It Va OFMT

.It Va RS

output format for numbers (default

Input record separator (default newline).

.Qq Li %.6g )

.It Va SUBSEP

separates multiple subscripts (default 034)

Separates multiple subscripts (default 034).

.It Va ARGC

argument count, assignable

.It Va ARGV

argument array, assignable;

non-null members are taken as filenames

.It Va ENVIRON

array of environment variables; subscripts are names.

.El

.Pp

Functions may be defined (at the position of a pattern-action statement)

Line 487

Line 500

.Pp

.Dl function foo(a, b, c) { ...; return x }

.Pp

Parameters are passed by value if scalar and by reference if array name;

Parameters are passed by value if scalar, and by reference if array name;

functions may be called recursively.

Parameters are local to the function; all other variables are global.

Thus local variables may be created by providing excess parameters in

the function definition.

.Sh EXAMPLES

Print lines longer than 72 characters:

.Pp

.Dl length($0) > 72

Print lines longer than 72 characters.

.Pp

Print first two fields in opposite order:

.Pp

.Dl { print $2, $1 }

Print first two fields in opposite order.

.Pp

Same, with input fields separated by comma and/or blanks and tabs:

.Bd -literal -offset indent

BEGIN { FS = ",[ \et]*|[ \et]+" }

{ print $2, $1 }

.Ed

Same, with input fields separated by comma and/or blanks and tabs.

.Pp

Add up first column, print sum and average:

.Bd -literal -offset indent

{ s += $1 }

END { print "sum is", s, " average is", s/NR }

.Ed

Add up first column, print sum and average.

.Pp

Print all lines between start/stop pairs:

.Pp

.Dl /start/, /stop/

Print all lines between start/stop pairs.

.Pp

Simulate echo(1):

.Bd -literal -offset indent

BEGIN { # Simulate echo(1)

for (i = 1; i < ARGC; i++) printf "%s ", ARGV[i]

Line 518

Line 538

exit }

.Ed

.Sh SEE ALSO

.Xr egrep 1 ,

.Xr lex 1 ,

.Xr sed 1

.Xr sed 1 ,

.Xr printf 3

.Rs

.%A A. V. Aho

.%A B. W. Kernighan