Trouble with a string

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

Hello All, I'm trying to create a string to ultimately copy a file from one location to the other, but when i try to append a common string to the end of the file I'm not getting the results that I expect. Each file suffix is -vda.img with the prefix all completely random. Here is what I have so far..


$OLDVMDIR = "/sunstorage_kvm_images/kvm_images/images";  #Current Dire
+ctory
$NEWVMDIR = "/sunstorage_kvm_images/kvm_images/images_new";  #Target (
+New) Directory
$VMSFX = "\-vda\.img";  #File suffix for each file

<snip>

        @VMSHUT = `cat /tmp/virshlist_shutdown`;
          foreach $VMSHUT (@VMSHUT)
            {
              $VMFILE = $OLDVMDIR . $VMSHUT . $VMSFX;
              print "$VMFILE $NEWVMDIR \n";
            }
[download]

What I'm expecting is it to print something like this..

/sunstorage_kvm_images/kvm_images/images/Debian-vda.img /sunstorage_kvm_images/kvm_images/images_new

Instead I'm getting..

/sunstorage_kvm_images/kvm_images/imagesDebian

-vda.img /sunstorage_kvm_images/kvm_images/images_new

TIA

Comment on Trouble with a string Download Code

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Re: Trouble with a string by johngg (Canon) on Dec 11, 2012 at 23:14 UTC
@VMSHUT = `cat /tmp/virshlist_shutdown`; You will also need to remove the line terminator from each line of the array using chomp otherwise each file name will have a spurious line terminator at the end. $ cat zzz Line 1 Line 2 Line 3 $ perl -e ' > @lines = `cat zzz`; > print qq{>$_<\n} for @lines;' >Line 1 < >Line 2 < >Line 3 < $ perl -e ' > @lines = `cat zzz`; > chomp @lines; > print qq{>$_<\n} for @lines;' >Line 1< >Line 2< >Line 3< $ [download] I hope this is helpful. Cheers, JohnGG	[reply] [d/l] [select]
Re^2: Trouble with a string by Anonymous Monk on Dec 11, 2012 at 23:21 UTC
Thanks, I think it's the chomp. It's always the simple things.. And it doesn't help that I'm 10 years rusty and not the good with PERL to begin with. :)	[reply]
Re: Trouble with a string by kennethk (Abbot) on Dec 11, 2012 at 23:16 UTC
Assuming your post's whitespace has not been mangled (you should wrap output in `<code>` tags to avoid that), your issue is that the results from the external call ends with a newline character. This is easily fixed with chomp: $OLDVMDIR = "/sunstorage_kvm_images/kvm_images/images"; #Current Dire +ctory $NEWVMDIR = "/sunstorage_kvm_images/kvm_images/images_new"; #Target ( +New) Directory $VMSFX = "\-vda\.img"; #File suffix for each file <snip> @VMSHUT = `cat /tmp/virshlist_shutdown`; chomp(@VMSHUT); foreach $VMSHUT (@VMSHUT) { $VMFILE = $OLDVMDIR . $VMSHUT . $VMSFX; print "$VMFILE $NEWVMDIR \n"; } [download] #11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.	[reply] [d/l] [select]
Re: Trouble with a string by Anonymous Monk on Dec 11, 2012 at 22:42 UTC
What I'm expecting is it to print something like this.. You're expecting the wrong thing, concatenation operator does not perform substitutions. Use the substitution operator. Read perlintro, and follow the rabbit hole :) Write to existing file with character insert (tags: in place edit EDIT AND BACKUP FILES SAFELY ARGV::readonly Iterator::Diamond Iterator::Files -pi.orig -pi.bak )	[reply]

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