Re^2: Query on Perl system command

When I modified

system 'echo "$filename.txt\n$filename.xls\n" | phylip';

with

qq(echo "$filename.txt\n$filename.xls\n" | phylip );

OR with

qq~echo "$filename.txt\n$filename.xls\n" | phylip ~;

I get the following error message

"Useless use of string in void context at alignment.pl line 75."

Any idea, why this is happening ? (I am newbie to perl)

I appreciate your help

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Re^3: Query on Perl system command by ww (Archbishop) on Mar 04, 2011 at 13:42 UTC
I'm a newbie to your code. Which is / what's in "Line 75?"	[reply]
Re^4: Query on Perl system command by Anonymous Monk on Mar 04, 2011 at 13:46 UTC
Oops... I copied entire error message !! `qq(echo "$filename.txt\n$filename.xls\n" \| phylip );` [download] This piece of code is in line 75	[reply] [d/l]
Re^4: Query on Perl system command by Anonymous Monk on Mar 04, 2011 at 13:58 UTC
If you allow me to complicate my script, The complete system command looks like this... `system 'echo "4\n6\n3\n5\n\n1\n$filename.fsmi\n5\n$filename.phb\n111\n +1000\n4\n$filename.ph\n$filename.dst\n\n2\n" \| phylip';` [download] phylip has many options, and user have to choose the option by pressing 1 or 2 or 3 or 4 ... etc. The point of giving output file name comes after choosing many such options. When I run "phylip" program separately (by "seperately", I mean, running "phylip" outside perl script) I type 1,2 or 3...etc and press ENTER key to choose that option. When I am calling "phylip" inside perl script, I use "\n" as a substitute for ENTER key	[reply] [d/l]