Replace a string after a word

[nithins]

Hi monks, How to replace string after matching with a certain word in a file?

For example, i have a string in file say "user={hhhfj}jshdfjhdfjh\=" i want to match for "user=" , if match is successful i want to replace this "{hhhfj}jshdfjhdfjh\=" string with my own value & new value should be written to file i,e "user=newvalue".

[kcott]

G'day nithins,

A little more information regarding the file and the string to be replaced would have been useful. For instance, how big is the file? how many replacements are possible in the file? if more than one, how many replacements are possible per record? Also, are there any constraints such as time, memory or disk space?

Bearing in mind the unknowns, the following (pm_1069470.pl) may be suitable for your needs:

#!/usr/bin/env perl

use strict;
use warnings;
use autodie;

use Tie::File;

tie my @records, 'Tie::File', 'pm_1069470.txt';
s/user={hhhfj}jshdfjhdfjh\\=/user=newvalue/ for @records;
untie @records;

Sample run:

$ cat pm_1069470.txt
blah blah blah
user={hhhfj}jshdfjhdfjh\=
whatever
user=something else
user={hhhfj}jshdfjhdfjh\=
other data

$ pm_1069470.pl

$ cat pm_1069470.txt
blah blah blah
user=newvalue
whatever
user=something else
user=newvalue
other data

[walto]

As I understood you want the filename to be user=newvalue and the string "user=newvalue" to be written to that file:

#!/usr/bin/perl
#
#
use strict;
use warnings;

my $teststring = '"user={hhhfj}jshdfjhdfjh\="';
my $own_value  = "newvalue";

if ( $teststring =~ /\"user=.*/ ) {
    $teststring =~ s /\"user=.*/\"user=$own_value\"/;
    my $filename = $teststring;
    print $teststring, "\n";

    $filename =~ s/\"//g;    #you don't want " in an filename
    open my $outfile, ">", $filename;
    print $outfile $teststring;
    close $outfile;
}

[Anonymous Monk]

What you could do is use the built-in string functions like index() and substr(). You could also use regular expressions.

[nithins]

Thank you guys!!. Your solutions helped me a lot...