Options to awk scripts

[Steve Keller]

Is there a way to pass options to awk scripts, like

awk -f script.awk -a

and handle the -a in my script? It seems when called like above, -a is
handled (and not understood) by awk itself. With

awk -f script.awk -- -a

I get the -a actually into the ARGV variable. However, I cannot put the -- into the

#!/usr/bin/awk -f

and call

./script.awk -a

That seems to be impossible. Probably a shell wrapper

#!/bin/sh

exec awk -- '...' $*

will work. Second, how can I handle this in the script? It seems

BEGIN { if (ARGV[1] == "-a") { opt_a = 1; ARGV[1] = "" } }

does work. Yet another way would be to handle options in the shell

#!/bin/sh

if [ $1 == "-a" ]; then shift; opt=-vopt_a=1; fi
exec awk $opt '...' $*

Is there some standard way to do this?

Steve

[Janis Papanagnou]

On 05.12.2021 12:24, Steve Keller wrote:
> Is there a way to pass options to awk scripts, like
>
> awk -f script.awk -a
>
> and handle the -a in my script? It seems when called like above, -a is
> handled (and not understood) by awk itself. With
>
> awk -f script.awk -- -a
>
> I get the -a actually into the ARGV variable. However, I cannot put the -- into the
>
> #!/usr/bin/awk -f
>
> and call
>
> ./script.awk -a
>
> That seems to be impossible. Probably a shell wrapper
>
> #!/bin/sh
>
> exec awk -- '...' $*

ITYM:

exec awk '...' "$@"

>
> will work. Second, how can I handle this in the script? It seems
>
> BEGIN { if (ARGV[1] == "-a") { opt_a = 1; ARGV[1] = "" } }
>
> does work. Yet another way would be to handle options in the shell
>
> #!/bin/sh
>
> if [ $1 == "-a" ]; then shift; opt=-vopt_a=1; fi
> exec awk $opt '...' $*
>
> Is there some standard way to do this?

Personally I wouldn't do that in awk but in shell (using getops) and
pass the control variables to awk, similar to what you have done, like

opt_a=0 # and other initializations
# here comes a while getopts-loop for all options
case $opt in
(a) opt_a=1 ;;
# other options as necessary
esac

awk -v opt_a="$opt_a" '...' "$@" # always pass all options!


Janis

>
> Steve
>

[Kenny McCormack]

In article <soi7hi$1jfv$1...@gioia.aioe.org>,

Steve Keller <keller...@gmx.de> wrote:
>Is there a way to pass options to awk scripts, like
>
> awk -f script.awk -a
>
>and handle the -a in my script? It seems when called like above, -a is
>handled (and not understood) by awk itself. With

Here's a way that works pretty well. I don't know if I'd call it
"standard" or not...

--- Cut Here ---
#!/bin/dash
exec gawk -f /dev/fd/3 -- "$@" 3<< 'EOF'
BEGIN { print ARGV[1] }
# (rest of AWK script goes here)
--- Cut Here ---

Run as: ./this -a

A couple of notes:
1) /bin/sh on Debian Linux system is actually "dash". So, you could use
/bin/sh instead. I prefer to always explicitly name my interpreter, rather
than letting it fall to chance.

2) I really should have put in "EOF" at the end, but I left it out to
illustrate that dash doesn't require it. bash does, well, sort of;
actually it works, but it generates a warning about it.

--
"We should always be disposed to believe that which appears to us to be
white is really black, if the hierarchy of the church so decides."

- Saint Ignatius Loyola (1491-1556) Founder of the Jesuit Order -