subroutines and arguments

natty_dread has asked for the wisdom of the Perl Monks concerning the following question:

I know there's a similar question out there, but it didn't help me. I'm trying to read a server list and perform actions on each server one at a time. However, I cannot access the variable. Here's some code:

open (SERVERLST, "< svr_daily.csv");

foreach my $svr (<SERVERLST>)
{
        chomp $svr;
       &ls_engine;
}

sub ls_engine {
        my $ls_eng = $_[0];
        system ("wdmlseng -e $ls_eng");
        }
[download]

My problem line of code is passing the global var $svr into the sub. I've tried my $ls_eng = shift (@_) AND my $ls_eng = $_; also.........I'm sure it's something small.

Comment on subroutines and arguments Download Code

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Re: subroutines and arguments by phaylon (Curate) on Apr 04, 2005 at 13:28 UTC
"I cannot access the variable" is a very very unfortunate description of what you want to do. $svr is declared with "my", so it's lexical. Here, you will only find it in your for-loop. Try: `for my $svr (<SERVERLST>) { chomp $svr; ls_engine ($svr); }` [download] And read up in 'perldoc perlsub' about what & actually does. Ordinary morality is for ordinary people. -- Aleister Crowley	[reply] [d/l]
Re: subroutines and arguments by Fletch (Bishop) on Apr 04, 2005 at 14:10 UTC
And not directly related to your problem, but ALWAYS CHECK THE RETURN VALUE FROM `open`! `open( SERVERLST, "<", "svr_daily.csv" ) or die "Can't open server dail +y CSV: $!\n";` [download]	[reply] [d/l] [select]
Re^2: subroutines and arguments by jhourcle (Prior) on Apr 05, 2005 at 01:19 UTC
And while you're at it, don't pass a single argument to system, either. Especially if you're passing in stuff from a file. (I'd recommend checking the lines from the file, even with the following changes): `open (SERVERLST, '<', 'svr_daily.csv') or die "Can't read from server daily CSV: $!"; foreach my $svr (<SERVERLST>) { chomp $svr; ls_engine($svr); } sub ls_engine { my $ls_eng = shift; system qw(wdmlseng -e), $ls_eng; }` [download] Update: per Fletch, fixed the mistake w/ qw(). Had previously been: `system qw(wdmlseng -e $ls_eng);`	[reply] [d/l] [select]
Re^3: subroutines and arguments by Fletch (Bishop) on Apr 05, 2005 at 03:07 UTC
`perl -le 'print for qw( $erm $do $you $really $want $qw? )'` Remember `qw()` is a compile time construct. But yes, if you're not sure about the pedigree of the contents of the file you don't want to pass a single scalar to `system`. Update: Not to mention that `qw()` is equivalent to `split(' ', q/STRING/)` to begin with and hence wouldn't do any interpolation.	[reply] [d/l] [select]
Re: subroutines and arguments by deibyz (Hermit) on Apr 04, 2005 at 13:28 UTC
Have a look at `perldoc perlsub`. You're not passing any parameter to your subroutine, try something like: `foreach my $svr (<SERVERLST>) { chomp $svr; ls_engine($svr); }` [download] Hope it helps, deibyz	[reply] [d/l] [select]
Re: subroutines and arguments by maa (Pilgrim) on Apr 04, 2005 at 13:29 UTC
why not try: `ls_engine($svr);` instead?	[reply] [d/l]


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