How to call subroutines with parameters from unix shell

Question

I am working with different subroutines of a Perl script. It is possible to call a single subroutine from the Perl script via the Unix shell like:

simplified examples:

perl automated_mailing.pl inf

then the function inform_user from automated_mailing.pl gets called. This is realized through a dispatch table:

my %functions = (
  inf=> \&inform_user,
);

inform_user looks like

sub inform_user{
    print "inform user: Angelo";

    ...some other stuff...
}

The question now is, how to replace "Angelo" with a variable and call it from shell like:

sub inform_user{
    my ($to)=@_;
    print "inform user: $to";
}

This call does not work:

perl automated_mailing.pl inf("Brian")

How is this be done correctly?

Dave Cross · Accepted Answer · 2020-08-17 10:42:04Z

4

You need to pass the arguments as separate command-line parameters:
```
perl automated_mailing.pl inf Brian
```

You need to pass the command-line parameters onto the subroutine that you call:

my ($func, @args) = @ARGV;

# And then later...

if (exists $functions{$func}) {
  $functions{$func}->(@args);
} else {
  die "$func is not a recognised function\n";
}

You haven't shown the code for the actual use of the dispatch table - so my second point is a bit of guesswork.

answered Aug 17, 2020 at 10:42

Dave Cross

69.5k3 gold badges55 silver badges101 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Angelo Uitz · Accepted Answer · 2020-08-17 12:21:59Z

0

With the given hint i reached exactly what i wanted. the programm now looks like:

use warnings;
use strict;

sub inform_user{
    my @to = @ARGV;
    print "inform user: $to[0]";
}

my %functions = (
  inform_user=> \&inform_user,
);

my $function = shift;

if (exists $functions{$function}) {
  $functions{$function}->();
} else {
  die "There is no function called $function available\n";
}

and the output is:

>> perl automated_mailing.pl inf Brian
>> inform user: Brian

answered Aug 17, 2020 at 12:21

Angelo Uitz

876 bronze badges

1 Comment

Dave Cross Over a year ago

I'd really recommend passing @ARGV as a parameter when calling $functions{$function}->() rather than using it as a global within the subroutine.

Collectives™ on Stack Overflow

How to call subroutines with parameters from unix shell

2 Answers 2

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related