Unix in a Nutshell, 4th Edition

Standard Options

The standard options are:

-F fs

Set the field separator to fs. This is the same as setting the built-in variable FS. POSIX awk allows fs to be a regular expression. Each input line, or record, is divided into fields by white space (spaces or TABs) or by some other user-definable 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

Many examples are shown later in the section "Simple Pattern-Action Examples.”