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

I need to write a script that opens a file and either:

1) deletes the last line and replaces it. or alternatively.

2) compares the last line and if it is not equal to what I need it to be then it replaces it. I think option 1 will be simpler, so I'm going with that. However, the line that I need to inset must have the file name in it. ie: File name ABCD Replaced Line: <xxxx.xxx.xxx.xxx, "xxx", xx_ABCD, xxx="">

so I open my file by: 
#Takes file name from command prompt
#Then assigns the name to str fileName
$fileName = INFILE;

#open the file and copy to an array
open(INFILE) || die("Cannot Open File");
@aFile = <INFILE>;
close(INFILE);


# How do I get the script to continue if line 6 is
# already deleted?
# Delete line 6
splice(@aFile,5) || die("Line 6 is already deleted");

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This is where I am stuck. I need to append the end of the file with a long string (see example above) that includes the file name. How difficult would it be to implement a test of the last string and output if the change had been made or not? Any assistance would be greatly appreciated. Thanks in advance

Replies are listed 'Best First'.
Re: Find and Replace
by kiruthika.bkite (Scribe) on Mar 25, 2010 at 03:53 UTC 
    use strict;
use warnings;
use Data::Dumper;
use Tie::File;

my @array;

tie @array,'Tie::File',$ARGV[0];
$array[-1]= qq(<xxxx.xxx.xxx.xxx, "xxx", xx_$ARGV[0], xxx="">);
print Dumper(\@array);

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Re: Find and Replace
by zwon (Abbot) on Mar 24, 2010 at 21:17 UTC

    Didn't actually get what do you want, but here's the code that assigns new value to line 6: 

    use strict;
use warnings;

my $fileName = shift;

#open the file and copy to an array
open my $fh, "<", $fileName or die "Cannot Open File: $!";
my @aFile = <$fh>;
close $fh;

# use $aFile[-1] for the last line, and $aFile[5] for the 6th line
$aFile[5] = qq(<xxxx.xxx.xxx.xxx, "xxx", xx_$fileName, xxx="">);

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Re: Find and Replace
by toolic (Bishop) on Mar 24, 2010 at 21:21 UTC
    Since you are already treating your file like an array of lines, you might be interested in Tie::File.

    Also, your code has major problems: use strict and warnings. Compiling your code generates warnings: 

    perl -wc -Mdiagnostics 830674.pl

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    This generates errors: 
    perl -wc -Mdiagnostics -Mstrict 830674.pl

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Re: Find and Replace
by Anonymous Monk on Mar 24, 2010 at 21:09 UTC
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Re: Find and Replace
by PyrexKidd (Monk) on Mar 25, 2010 at 16:03 UTC

    so here's what I've come up with. any suggestions for debugging this script? 

    use strict;
use warnings;
use Fcntl qw(:flock :seek);

my($fileName) = $ARGV[0];
print("$fileName \n");

#open the file and copy to an array
open(INFILE, $ARGV[0]) || die("Cannot Open File");
my(@aFile) = <INFILE>;
close(INFILE);


# Delete line 6
splice(@aFile,5) || die("Line 6 is already deleted");

open(OUTFILE,">$fileName") || die("Cannot Open File");
flock(OUTFILE, LOCK_EX);
seek(OUTFILE, 0, SEEK_SET);
print OUTFILE @aFile;

print OUTFILE "<APPLICATION APP_FILE_PATH=\"xxxxxx" CONFIG_FILES=\"xxx
+x/$fileName, MISC_FILES=\"\" LOG_FILE_DIRECTORY=\"\" OVERRIDES_DIRECT
+ORY=\"\" CONTACTS_DIRECTORY=\"\" LICENSE_DIRECTORY=\"\"/>";
close(OUTFILE);

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      It looks like you are working with an XML file so you should probably be using something like XML::Twig or XML::TreeBuilder to manipulate the data.

      Aside from that, the first thing to do is get your code passing strictures. As presented there is an unquoted " that generates an error. Using qq instead of a bare " quoted string would help a lot. eg:

      print OUTFILE qq~<APPLICATION APP_FILE_PATH="xxxxxx" CONFIG_FILES="xxx
+x...~;

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      True laziness is hard work
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