literal meaning of a variable

s_gaurav1091 has asked for the wisdom of the Perl Monks concerning the following question:

hi monks, I am struck up at a place.I am storing a value in one variable and then I am trying to find that variable from a file with the help of grep. for example my $find = "ObjectEventReceiverService"; now I am executing a command through the script

my $date = `date +20%y/%m/%d `;
@array = `grep $date $ENV{JBOSS_HOME}/log/wrapper.log |grep "$find sta
+rted"`;
[download]

My problem is that the grep command is not taking the value of $find as "ObjectEventReceiverService" instead its searching for $find.Can anyone suggest that what I should do here????

Comment on literal meaning of a variable Download Code

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Re: literal meaning of a variable by brian_d_foy (Abbot) on Feb 27, 2006 at 05:54 UTC
Is this your actual code? You'll probably want to `chomp` that date because it's coming with a newline with messes up the `grep`. Even better would be doing that directly in Perl. :) The backticks are a double-quoted context, so variables interpolate. Ensure you're getting what you think you're getting by changing the backticks to a `print`. `print qq(grep $date $ENV{JBOSS_HOME}/log/wrapper.log \| grep "$find sta +rted");` [download] -- brian d foy <brian@stonehenge.com> Subscribe to The Perl Review	[reply] [d/l] [select]
Re: literal meaning of a variable by McDarren (Abbot) on Feb 27, 2006 at 06:01 UTC
Can anyone suggest that what I should do here???? Well, yes. If it was me - rather than calling the shell - I would open the file, and then search for the line/s of interest. Something like (untested): `my $file = "$ENV{JBOSS_HOME}/log/wrapper.log"; open IN, "<$file" or die "Cannot open $file:$!\n"; while (<IN>) { chomp; next if ($_ !~ /$find/); next if ($_ !~ /$date/); push @array, $_; }` [download] Cheers, Darren :) Update: Fixed code snippet, as per revdiablo below :)	[reply] [d/l]
Re^2: literal meaning of a variable by revdiablo (Prior) on Feb 27, 2006 at 06:17 UTC
Except `!~` is a binary operator. Perhaps you meant: `... next if !/$find/; next if !/$date/; ...` [download] Though I would be tempted to instead use: `... next unless /$find/; next unless /$date/; ...` [download]	[reply] [d/l] [select]
Re^3: literal meaning of a variable by McDarren (Abbot) on Feb 27, 2006 at 06:32 UTC
Except !~ is a binary operator. heh... well, I did say it was untested :) What I meant was: `next if ($_ !~ /$find/);` Although I guess in that context it's essentially the same as: `next if !/$find/;` yes? Ever since I read TheDamian's PBP, I tend to try and avoid unless :)	[reply] [d/l] [select]