in reply to perl one liner to replace matching string

Hello vinoth.ree,

With warnings:

use strict;
use warnings;

while (<DATA>)
{
    s/(@Filetyp\s*?:)/\1c/;
    print;
}

__DATA__
@header_start
@Titel         : init 
@Filename      : test.c
@Filetyp       :
@Version       : 0001
@Produkt       : xx
@delivery      : xx
@date          : 20160610
@header_end

[download]

Output:

 0:54 >perl 1895_SoPW.pl
Possible unintended interpolation of @Filetyp in string at 1895_SoPW.p
+l line 18.
\1 better written as $1 at 1895_SoPW.pl line 18.
Global symbol "@Filetyp" requires explicit package name (did you forge
+t to declare "my @Filetyp"?) at 1895_SoPW.pl line 18.
Execution of 1895_SoPW.pl aborted due to compilation errors.

17:41 >

[download]

Perl sees @Filetyp as an (empty) array. Escape the sigil (and change \1 to $1):

s/(\@Filetyp\s*?:)/$1 c/;.

Output:

17:44 >perl 1895_SoPW.pl
@header_start
@Titel         : init
@Filename      : test.c
@Filetyp       : c
@Version       : 0001
@Produkt       : xx
@delivery      : xx
@date          : 20160610
@header_end

17:44 >

[download]

Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

Replies are listed 'Best First'.
Re^2: perl one liner to replace matching string
by vinoth.ree (Monsignor) on Jun 10, 2018 at 08:05 UTC

    I tried the below perl one liner to replace the "@Filetyp :" as "@Filetyp :c"

    my $ext='c';
qx("perl -p -i -e \"s/(\@Filetyp\\s*?:)/\\1$ext/\" /path/test.c");

    [download]

    I am already doing it.Could you pls try like above perl one liner to replace the string?

    All is well. I learn by answering your questions...
[reply]
[d/l]

      Ok, I get the same result as you reported. Playing around with it, I had to add two additional backslashes to get it to work as desired (not sure why):

      my $ext='c';
qx("perl -p -i.bak -e \"s/(\\\@Filetyp\\s*?:)/\\1$ext/\" ./path/test.c
+");
#                          ^^

      [download]

      (Note: I also had to specify an extension for the backup file.) This is on Windows; if your O/S is different, it may treat the backslashes differently.

      Hope that helps,

      Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

[reply]
[d/l]
        In response to: not sure why

        Similar findings: here and it was pretty heavily analyzed by AnomalousMonk in the following posts

[reply]

        You are right I am writing this for windows, If it is linux/unix I could have used sed/awk.

        All is well. I learn by answering your questions...
[reply]
[d/l]

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