I know this kind of questions have been asked already many times before. The reason why I come here again is that I feel like I've missed something simple and fundamental.
Is it possible to make this kind of search-replace routine better. For example without opening same file twice. Also speed related advices are welcome.
Please notice that this works with multiline matches and replaces also multiline strings.
#!/bin/perl -w -0777
local $/ = undef;
open INFILE, $full_file_path or die "Could not open file. $!";
$string = <INFILE>;
close INFILE;
$string =~ s/START.*STOP/$replace_string/sm;
open OUTFILE, ">", $full_file_path or die "Could not open file. $!";
print OUTFILE ($string);
close OUTFILE;
This kind of search and replace can be accomplished with a one-liner such as -
perl -i -pe 's/START.*STOP/replace_string/g' file_to_change
For more ways to accomplish the same thing check out this thread. To handle multi-line searches use the following command -
perl -i -pe 'BEGIN{undef $/;} s/START.*STOP/replace_string/smg' file_to_change
In order to convert the following code from a one-liner to a perl program have a look at the perlrun documentation.
If you really find the need to convert this into a working program then just let Perl handle the file opening/closing for you.
#!/usr/bin/perl -pi
#multi-line in place substitute - subs.pl
use strict;
use warnings;
BEGIN {undef $/;}
s/START.*STOP/replace_string/smg;
You can then call the script with the filename as the first argument
$perl subs.pl file_to_change
If you want a more meatier script where you get to handle the file open/close operations(don't we love all those 'die' statements) then have a look at the example in perlrun under the -i[extension] switch.