There are two ways to run
awk—with an explicit program or with
one or more program files. Here are templates for both of them; items
enclosed in […] in these templates are optional:
awk [options] -f progfile [--] file … awk [options] [--] 'program' file …
In addition to traditional one-letter POSIX-style options,
supports GNU long options.
It is possible to invoke
awk with an empty program:
awk '' datafile1 datafile2
Doing so makes little sense, though;
silently when given an empty program.
been specified on the command line,
gawk issues a
warning that the program is empty.