Linux in a Nutshell, Fifth Edition

Command-Line Syntax | 771

gawk

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Standard Options

The standard options are:

-Ffs

Set the field separator to fs. This is the same as setting the built-in variable

FS. gawk allows fs to be a regular expression. Each input line, or record,is

divided into fields by whitespace (spaces or tabs) or by some other user-defin-

able field separator. Fields are referred to by the variables $1, $2,…, $n. $0

refers to the entire record.

-v var=value

Assign a value to variable var. This allows assignment before the script begins

execution.

For example, to print the first three (colon-separated) fields of each record on

separate lines:

awk -F: '{ print $1; print $2; print $3 }' /etc/passwd

Numerous examples are shown later in “Simple Pattern-Procedure Examples.”

Important gawk Options

Besides the standard command line options, gawk has a large number of addi-

tional options. This section lists those of most value in day-to-day use. Any

unique abbreviation of these options is acceptable.

--dump-variables[=file]

When the program has finished running, print a sorted list of global vari-

ables, their types, and their final values to file. The default file is awkvars.out.

--gen-po

Read the awk program and print all strings marked as translatable to stan-

dard output in the form of a GNU gettext Portable Object file. ...