gawk [options] 'script' var=value file(s)
gawk [options] -f scriptfile var=value file(s)
You can specify a script directly on the command line, or
you can store a script in a scriptfile and specify it with
-f.
Multiple -f options are allowed;
awk concatenates the files. This feature is useful
for including libraries.
gawk operates on one or more input
files. If none are specified (or if - is specified), gawk
reads from the standard input.
Variables can be assigned a value on the command line.
The value assigned to a variable can be a literal, a shell variable
($name), or a command substitution (`cmd`),
but the value is available only after a line of input is read (i.e.,
after the BEGIN statement).
For example, to
print the first three (colon-separated) fields of the password file,
use -F to set the field separator to a colon:
gawk -F: '{print $1; print $2; print $3}' /etc/passwd