Perl in place edit within a script

Question

I need to edit a file in place within a perl script, so the oft used one liner:

perl -p -e s/<value>/<value>/ig

will not work for this situation. How do I get the same results from within a perl script?

open(CRONTAB, "+<file" || die "...";

while (<CRONTAB>) { 
   if ($_ =~ /value/) {  
      s/^\#+//;  
      print "$_\n";  
   }  
}

My print is showing exactly what I want. It's just the in place edit that I'm looking for.

Answer 1

do {
  local $^I='.bak'; # see perlvar(1)
  local @ARGV=("file");
  while(<>){
    s/<value>/<value>/ig;
    print;
  }
};

Beware though: $^I like perl's -i isn't crashproof.

Answer 2

Your edit appear pretty simple. Have you considered simply using sed with the -i option?

Answer 3

Try this, based on the translation of -i in perldoc perlrun:

use strict;
use warnings;
my $filename = "something";
my $extension = '.orig';
while (<>) {
    my $backup;
    if ($extension !~ /\*/) {
        $backup = $filename . $extension;
    }
    else {
        ($backup = $extension) =~ s/\*/$filename/g;
    }
    rename $filename, $backup;
    open my $outfile, '>', $filename;
    select $outfile;
    s/^\#+// if /value/; 
}
continue {
    print;  # this prints to original filename
}
select STDOUT;

Answer 4

use File::Inplace

Also, it has commit/rollback after you've got all your changes in place for a file....