one liner increment of variable value in text file using perl

Question

I have variable in file of perl program. I only want to increase value vertically position of $[0] as $[1] $[2] , as each $[0] variable right now have base 64 to utf-8 values.

I only want to change $[0] to increase value until end of file.

I tried command of perl as mentioned

perl -pi -e 's/U[0](\d+)[0].($1+1)/e' 25k.list

syntax error at -e line 1, near "](" Unmatched [ in regex; marked by <-- HERE in m/ <-- HERE ,/ at -e line 1.

Added:

some data in file:

$U[0] = "\data1\fileloader.ini";
$U[0] = "\data1\data2\crame\crame.ini";
$U[0] = "\data1\data2\data3\files\setup.exe";
$U[0] = "\data1\data2\data3\data4\WINDOWS\win.ini";

What I want, increase $U[from 0, untill it no longer occur], it should be:

$U[0] = "\data1\fileloader.ini";
$U[1] = "\data1\data2\crame\crame.ini";
$U[2] = "\data1\data2\data3\files\setup.exe";
$U[3] = "\data1\data2\data3\data4\WINDOWS\win.ini";

only affecting $U[ ] 

Answer 1

The "Syntax error" comes from the fact that your regexp is missing the / which should separate search pattern from replacement part. Additionally you want to execute the replacement part and I think the [] are meatn literally. So my best guess is, your s/p/r/ should be: s/U\\[0\\](\\d+)/"U[0]".($1+1)/e

Answer 2

The s/// expression that works for this case is:

s/\$U\[0\]/"\$U[".$c++."]"/ge

This means: Replace every occurence of $U[0] with $U[n] , n being the next integer starting from 0 .

Please read: https://perldoc.perl.org/perlop.html about s/PATTERN/REPLACEMENT/ .

Answer 3

This seems to do what you want.

#!/usr/bin/perl

use strict;
use warnings;

my $x = 0;

while (<DATA>) {
  s/U\[0]/'U[' . $x++ . ']'/e;
  print;
}

__DATA__
$U[0] = "\data1\fileloader.ini";
$U[0] = "\data1\data2\crame\crame.ini";
$U[0] = "\data1\data2\data3\files\setup.exe";
$U[0] = "\data1\data2\data3\data4\WINDOWS\win.ini";

The output I get is:

$U[0] = "\data1\fileloader.ini";
$U[1] = "\data1\data2\crame\crame.ini";
$U[2] = "\data1\data2\data3\files\setup.exe";
$U[3] = "\data1\data2\data3\data4\WINDOWS\win.ini";

Like the other answers, I've basically made three fixes here.

• Stop [0] being interpreted as a character class.
• Correct the syntax of your s/.../.../ expression.
• Ignore $1 and use an incrementing variable for the replacement integer.