Question

I cannot get this to work.

#!/usr/bin/perl -w
use strict;
use CGI::Carp qw(fatalsToBrowser warningsToBrowser);
my $id='123456'; 
my $filetoopen = '/home/user/public/somefile.txt';

file contains:

123456
234564
364899
437373

So…
A bunch of other subs and code

if(-s $filetoopen){
     perl -n -i.bak -e "print unless /^$id$,/" $filetoopen;
}

I need to remove the line that matches $id from file $filetoopen

But, I don’t want script to “crash” if $id is not in $filetoopen either.

This is in a .pl scripts sub, not being run from command line.

I think I am close but, after reading for hours here, I had to resort to posting the question.

Will this even work in a script?

I tried TIE with success but, I need to know alternatively how to do this without TIE::FILE.

When I tried I got the error:

syntax error at mylearningcurve.pl line 456, near “bak -e “

Thanks for teaching this old dog…

Answer 1

First of all (this is not the cause of your problem) $, (aka $OUTPUT_FIELD_SEPARATOR) defaults to undef, I’m not sure why you are using it in the regex. I have a feeling the comma was a typo.

It’s unclear if you are calling this from a shell script or from Perl?

---

If from Perl, you should not call a nested Perl interpreter at all.

If the file is small, slurp it in and print:

use File::Slurp;
my @lines = read_file($filename);
write_file($filename, grep { ! /^$id$/ } @lines);

If the file is large, read line by line as a filter.

use File::Copy;
move($filename, "$filename.old") or die "Can not rename: $!\n";
open(my $fh_old, "<", "$filename.old") or die "Can not open $filename.old: $!\n";
open(my $fh, ">", $filename) or die "Can not open $filename: $!\n";
while my $line (<$fh_old>) {
    next if $line =~ /^id$/;
    print $fh $_;
}
close($fh_old);
close($fh);

---

If from a shell script, this worked for me:

$ cat x1
123456
234564
364899
437373

$ perl -n -i.bak -e "print unless /^$id$/" x1

$ cat x1
234564
364899
437373