gawk: option requires an argument -- f
Usage: gawk [POSIX or GNU style options] -f progfile [--] file ...
Usage: gawk [POSIX or GNU style options] [--] 'program' file ...
POSIX options:		GNU long options: (standard)
	-f progfile		--file=progfile
	-F fs			--field-separator=fs
	-v var=val		--assign=var=val
POSIX options:		GNU long options: (extensions)
	-m[fr] val
	-b			--characters-as-bytes
	-c			--compat, --traditional
	-C			--copyleft, --copyright
	-d [file]		--dump-variables[=file]
	-e 'program-text'	--source='program-text'
	-E file			--exec=file
	-g			--gen-pot
	-h			--help, --usage
	-l [fatal]		--lint[=fatal]
	-L			--lint-old
	-n			--non-decimal-data
	-N			--use-lc-numeric
	-O			--optimize
	-p [file]		--profile[=file]
	-P			--posix
	-r			--re-interval
	-S			--sandbox
	-V			--version

To report bugs, see node `Bugs' in `gawk.info', which is
section `Reporting Problems and Bugs' in the printed version.

gawk is a pattern scanning and processing language.
By default it reads standard input and writes standard output.

Examples:
	gawk '{ sum += $1 }; END { print sum }' file
	gawk -F: '{ print $1 }' /etc/passwd