Using perl 5.8.0 on Solaris, I sometimes use system calls to manipulate a file or directory. This has worked well in the past, but this week a script failed trying to copy a file. The error message was "Illegal seek at ./script.pl line XXX", and the system call causing the error is here:

use strict;
system( "cp /analysis/fasta1.fa /analysis2/fasta1.fa" ) 
    or die print "Can't copy fasta file: $! \n";
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A friend at work said that in his experience, the return code from "system" isn't reliable when used that way. He said I should capture the actual return code from the system call and evaluate it. If it's not zero, there's an error and to print $! at that point. I followed his recommendation and the problem went away. Here's the code I used.

use strict;
&doSystemCommand(  "cp /analysis/fasta1.fa /analysis2/fasta1.fa"  );

sub doSystemCommand
{
    my $systemCommand = $_[0];

    print LOG "$0: Executing [$systemCommand] \n";
    my $returnCode = system( $systemCommand );

    if ( $returnCode != 0 ) 
    { 
        die "Failed executing [$systemCommand]\n"; 
    }
}
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Could you tell me more about what is happening here and why this eliminated the errors? Also, could you offer improvements in this function for handling system calls?