shellscript to Perl

[kluther]

Hello all, I've an existing shell-script, but I would like to rewrite it in Perl. I'm new to Perl and now I stumble on something. In my shell-script I have the following line:

if [ a`/usr/well561/bin/newlogfile 1` = aY ]; then
echo "true"
else
echo "false"
fi

when I do this in perl like this:

if (`/usr/well561/bin/well.newlogfile 1` eq Y) {
print "true";
}
else {
print "false";
}

I get an error about using Bareword "Y" in strict mode, when I take the strict mode out I don't get the right result. How should I rewrite the above in Perl. I've tried several things but they don't work, mostly an error on Bareword "Y". Advise please Thanx Kluther

[LanX]

Enclose the Y into quotes 'Y', to transform a bareword into a string-literal.

PS: please enclose your code in <code>...</code> tags.

[Anonymous Monk]

"Put quotes around any strings"

'Put quotes around any strings'

Before you try converting a program, read about the basic syntax, at minimum perlintro.

There is also Tutorials , Learn Perl in about 2 hours 30 minutes, http://learn.perl.org/books/beginning-perl/, Modern Perl

[eyepopslikeamosquito]

Also, note that shell backticks remove the trailing newline, while Perl backticks preserve it.

Given you are just starting with Perl, it is a good idea to sprinkle print statements and error checks in your script to help you understand what is going on. To get you started, try this:

use strict;
use warnings;
my $cmd = '/usr/well561/bin/well.newlogfile';
-f $cmd or die "error: '$cmd' not found";
-x $cmd or die "error: '$cmd' not executable";
my $out = `$cmd 1`;
my $rc = $? >> 8;
print "command exit code is $rc\n";
$rc == 0 or warn "warning: command returned $rc\n";
chomp $out;    # remove trailing new line from command output
print "command output:$out:\n";
if ($out eq 'Y')
{
   print "command returned Y\n";
}

Study the script above, referring to the Perl documentation, and you should be on your way to rewriting your old shell scripts in Perl. As for learning Perl, take a look at learn.perl.org and Perl Tutorial Hub. Good luck!

[osbosb]

http://perldoc.perl.org/functions/system.html

http://perldoc.perl.org/perlop.html#Quote-Like-Operators <-- read about qx.

[muppetjones]

Perhaps I'm misinterpreting your post, but is "Y" a variable or a character?
The compiler is complaining because it doesn't know how to handle 'Y' -- you need to either use it as a variable, i.e., $Y or surround it by quotes, i.e., 'Y'.

As a side note, it is generally slightly faster to use single quotes rather than interpolating a variable or special character, e.g,
'Hello world.' vs. "Hello world",
'The number is '.$num vs "The number is $num", or
'Hello world.'."\n" vs "Hello world\n".