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

Would there be an easier way to do this in perl? 
#!/bin/tcsh
#1. Create a file of all disk images from the Netbackup catalog that N
+etbackup thinks is on disk.

echo "Creating list of all images that Netbackup thinks is on disk."
cp /dev/null catall
grep "F:\\backup" cat.txt | sed -e "s/F:\\backup\\/\*/g" | awk -F\* '{
+print "F:\\backup\\" $2}' >> catall
grep "G:\\backup" cat.txt | sed -e "s/G:\\backup\\/\*/g" | awk -F\* '{
+print "G:\\backup\\" $2}' >> catall
grep "H:\\backup" cat.txt | sed -e "s/H:\\backup\\/\*/g" | awk -F\* '{
+print "H:\\backup\\" $2}' >> catall

#2.  Create file of what's on disk

echo "Create file listing of all images on disk."
cp /dev/null dirall
grep "_" Fdir.txt | awk '{print "F:\\backup\\" $5}' > dirall
grep "_" Gdir.txt | awk '{print "G:\\backup\\" $5}' >> dirall
grep "_" Hdir.txt | awk '{print "H:\\backup\\" $5}' >> dirall

#3. sort the files

echo "Sorting the two files"
sort catall > catall.srt
sort dirall > dirall.srt

#4. check em
 
echo "Checking the differences."
diff -u dirall.srt catall.srt |grep "^-" |grep -v "\-\-\-" |sed -e s/\
+-//g > delfile.list

#5. create batch file

echo "Creating a batch file to delete the files that Netbackup doesn't
+ know about."
awk '{print "del " $1}' delfile.list > delfile.bat

[download]

Retitled by g0n from 'tcsh'.

Replies are listed 'Best First'.
Re: Listing Files in a Directory (Translation From Shell Script)
by graff (Chancellor) on Sep 07, 2005 at 23:16 UTC
    Perl vs. tcsh?? No contest in this case. The perl version will be a lot easier and make more sense. (Run time is probably not an issue, but I expect it will run faster than the shell script + batch file.) 
    #!/usr/bin/perl

use strict;

my %files;

# load %files with names of all images on disk

for my $disk (qw/F G H/) {
    if ( open( I, $disk."dir.txt" )) {
        while (<I>) {
            next unless ( /_/ );
            my $name = "$disk:\\backup\\" . ( split )[4];
            $files{$name} = undef;
        }
    }
    else {
        warn "unable to open dir.txt for $disk: -- $!\n";
        next;
    }
}

# eliminate hash elements in %files if Netbackup thinks they are on di
+sk

if ( open( I, "cat.txt" )) {
    while (<I>) {
        if ( /([FGH]:\\backup\\)/ ) {
            my $path = $1;
            s/\Q$path\E/*/g;
            my $name = $path . ( split /\*/ )[1];
            delete $files{$name};
        }
    }
}
else {  # best to stop here if that last open failed:
    die "open failed for cat.txt: $!";
}

# delete files that are left in the hash

unlink for ( keys %files );

    [download]
    (I hoped to say the perl version would be shorter, but that would depend on how you measure script length -- the perl script above is more lines, but fewer characters compared to your shell script, and it does not require the creation of a separate batch file to be run at some other time. And of course, the perl could be shortened to fewer lines.)
[reply]
[d/l]
      It's the error checking that makes it longer, error checking that wasn't present in the original script. It's hard to complain that it's longer if one gets more functionality and reliability :)
[reply]
Re: Listing Files in a Directory (Translation From Shell Script)
by Tanktalus (Canon) on Sep 07, 2005 at 22:59 UTC

    There would be an easier way to do that in sed or awk!

    #1 ...

sed -e "s/.*([FGH]):\\backup\\/\1:\\backup\\ /" < cat.txt > catall

#2 ...

# (bourne shell syntax, sorry)
for d in F G H; do
  awk '/_/{print "'$d'":\\backup\\" $5 } < ${d}dir.txt
done > dirall

#3 ... could have done this above by piping through sort.

#4 & 5 ...

diff -u dirall.srt catall.src | sed -e '/---/d' -e '/^[^-]/d' -e 's/-/
+/g' -e 's/^/del /' > delfile.bat

    [download]

    But, to answer your question, yes, using some hashes, you could figure this out and even unlink them all directly without a batch file.

[reply]
[d/l]
Re: Listing Files in a Directory (Translation From Shell Script)
by Fletch (Bishop) on Sep 07, 2005 at 22:52 UTC

    Wow, I actually upvoted an AM post . . . (the who cares one)

    Yes you could do that in perl, but the questions to ask are:

    • Is it working now?
    • Do you have enough shell knowledge to maintain it?
    • Does it need to do anything different?

    If it's "yes yes no" then if it's not broke . . . . Otherwise go right ahead and rewrite it.

[reply]
Re: Listing Files in a Directory (Translation From Shell Script)
by Anonymous Monk on Sep 07, 2005 at 22:45 UTC
    Who cares?
[reply]

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