in reply to Need a little help appending lines

It's generally a bad idea to edit a file in place.

What I'd suggest is that you create a new file with the desired content, and the move the new file to the place of the old file.

You could first read things that you want to append into @list, and then do the "real" operation: 

use File::Copy; # for move()
open my $of, '<', $old_file or die "Can't read $old_file: $!";
open my $nf, '>', $new_file or die "Can't write $new_file: $!";
my $line_number = 0;
while (my $line = <$of>){
    chomp $line;
    print $nf $line, $list[$line_number];
}
close $nf;
close $of;
move $new_file, $old_file;

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Re^2: Need a little help appending lines
by shmem (Chancellor) on Sep 11, 2007 at 22:47 UTC
    It's generally a bad idea to edit a file in place.

    Is it? Why?

    --shmem 

    _($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}
[reply]
      It's a bad idea to edit a file in-place without a backup, let's just put it that way. Creating a separate output file from your source means your source *is* the backup. So moritz's point, a little less succinctly put, is, "Don't edit a file with important data unless you can undo any changes."

      (Or use version control.)
[reply]
        Precaution against data loss is an entirely different thing, though related. But that concern doesn't justify marking in-place edits as bad idea, more so generally.

        Perl wouldn't have the -i switch if doing in-place edits wasn't a good idea. Generally speaking.

        --shmem 

        _($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}
[reply]

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