for ($i=0;$i<=$#steps;$i++)
{
    open MIN_RUN, ">run";
    print MIN_RUN qq(/opt/sander -i $steps[$i].min -p ../$steps[$i].pr
+mtop -o $step[$i]$step[$i].e &\n);
    print MIN_RUN qq(/opt/sander -i $steps[$i].min -p ../../$steps[$i-
+1]/$step[$i-1].prmtop -o $step[$i]$step[$i-1].e &\n);
}

[download]

here is what is printed out in file run:
/opt/sander -i ele0.5.min -p ../ele0.5.prmtop -o .e &
/opt/sander -i ele0.5.min -p ../../ele1.0/.prmtop -o .e &

I got the error msg in these two "print" lines.

The correct "run" file is supposed to look like this:
/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 ele0.5ele1.0.e &

So what is going on here?

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

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