++jwkrahn and ++bichonfrise74.

Two other errors are lurking in the code.

  1. You are overwriting the run file on each loop. You probably just need to move the open to just before the loop.
  2. You are looping over for ($i=0;$i<=$#steps;$i++), ( which is better written as foreach my $i ( 0 .. $#steps ) ), but inside the loop you refer to $steps[$i-1]. On the first loop through, $i is 0, so $i-1 is -1, and $steps[-1] will give you the *last* element in the array. If that is what you meant to do, then fine. If not, then perhaps you need to start the loop index at 1 instead of 0?

Working, tested code:

#!/usr/bin/perl
use strict;
use warnings;

my @steps = ( 'ele1.0', 'ele0.5' );

die if @steps < 2; 
open my $MIN_RUN, '>', 'run'
    or die "Cannot open 'run': $!";

my $last_step = $steps[0];
for my $step ( @steps[1..$#steps] ) {
    print $MIN_RUN "/opt/sander -i $step.min -p ../$step.prmtop -o $st
+ep$step.e &\n";
    print $MIN_RUN "/opt/sander -i $step.min -p ../../$last_step/$last
+_step.prmtop -o $step$last_step.e &\n";
    $last_step = $step;
}

close $MIN_RUN or warn;

[download]
Output:
    /opt/sander -i ele0.5.min -p ../ele0.5.prmtop -o ele0.5ele0.5.e &
    /opt/sander -i ele0.5.min -p ../../ele1.0/ele1.0.prmtop -o ele0.5e
+le1.0.e &

[download]

In reply to Re: Use of uninitialized value in concatenation (.) or string by Util
in thread Use of uninitialized value in concatenation (.) or string by oscarjiao

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