Substituting variables while reading text file

Question

I have a text file as below and saved it as "file.txt"

"create variable $VAR alarm_object 0"

I am trying to read this in a perl script and printing it by substituting the "$VAR" variable

$VAR = TEMP_VAR
open (FILE,"<", "file.txt") or die $!;
        while (<FILE>) {
                chomp;
                eval(print "$_\n");
        }
        close (FILE);

I need the output as

"create variable TEMP_VAR alarm_object 0"

I tried to achieve this using eval function. It is not working as expected.

How can i achieve this in perl?

score 2 · Accepted Answer · edited Aug 06 '14 at 00:10

2

eval is too heavy of a tool for this job. Instead, just use a simple search and replace.

This basically substitutes '$VAR' with $sub for every line of your input file:

use strict;
use warnings;
use autodie;

my $sub = 'TEMP_VAR';

open my $fh, '<', 'file.txt';

while (<$fh>){
    print;             # Before
    s/\$VAR\b/$sub/g;
    print;             # After
}

Outputs:

"create variable $VAR alarm_object 0"
"create variable TEMP_VAR alarm_object 0"

edited Aug 06 '14 at 00:10

Miller

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answered Aug 05 '14 at 17:56

fugu

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Nor the while loop, seeing as it's just one line. But this way is a safer, more scalable approach, no? – fugu Aug 05 '14 at 18:07
Its working as mentioned above. File contains number of such Dollar Variables so while loop is required. correct? – Mohan Aug 06 '14 at 02:28

Substituting variables while reading text file

1 Answers1