Perl: How to exit from main script if exit criteria is in a subscript?-CodePudding

I have a script main.pl which contains a loop over a list. This loop calls a subscript sub.pl which contains an exit criteria. When the criteria is met the program exit only the subscript but not the main script. How I have to change the code to stop the main script?

main.pl:

use strict; 
use warnings;
    
my @list = qw (a b c);

foreach my $i (@list) {    
    my $cmd = "sub.pl $i";
    print "$cmd\n";        
    system($cmd);        
}

sub.pl:

use strict; 
use warnings;    
use Cwd;

my $dir0 = getcwd;    
open my $LOG, ">>$dir0/log.txt" or die "Cannot open log.txt: $!\n";

my $value = $ARGV[0];

if ( $value eq 'b') {
    print "\nExit from script 2\n";
    exit;
}

print $LOG "Value is $value\n";
close $LOG;

The STDOUT is:

# sub.pl a
# sub.pl b
# 
# Exit from script 2
# sub.pl c

And the $LOG output is:

# Value is a
# Value is c

I would like that the script stops at value b.

CodePudding user response：

sub.pl is always exiting at the end of the script, not just when you exit explicitly exit somewhere else. You can exit with a specific code in sub.pl:

exit 1 if $value eq "b";

and then look for the exit code in main.pl:

system( $cmd ) and last

CodePudding user response：

Adding to @AKHolland's answer...

In general unfortunately can't just check the exit code of system($cmd) as perl makes life difficult by multiplexing a lot more information than just the exit code into $?. [1] I would recommend always using code like this to check it.

system($cmd);
last if ( ($? >> 8) & 255);

[1] https://perldoc.perl.org/functions/system