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perl oneliner not works .pl script

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# 1  
Old 11-24-2010
perl oneliner not works .pl script
I am trying to take first 3 columns in a file which matches the word "abc", but i am getting the below error,
<error>
Global symbol "@F" requires explicit package name at ./new.pl
</error>

whereas when i give the below,grep abc /home/test/file.txt|perl -lane 'print \"$F[0] $F[1] $F[2]\" in unix prompt i am getting the result. When i use inside the perl script it fails. When i remove "use strict" it returns nothing.Please help me out


Code:
#!/usr/bin/perl
use strict;
use warnings;
print `grep abc /home/test/file.txt|perl -lane 'print \"$F[0] $F[1] $F[2]\"' > a.txt`;

Last edited by DukeNuke2; 11-30-2010 at 05:21 AM..
# 2  
Old 11-24-2010
Quote:
Originally Posted by anspks
I am trying to take first 3 columns in a file which matches the word "abc", but i am getting the below error,
<error>
Global symbol "@F" requires explicit package name at ./new.pl
</error>

whereas when i give the below,grep abc /home/test/file.txt|perl -lane 'print \"$F[0] $F[1] $F[2]\" in unix prompt i am getting the result. When i use inside the perl script it fails. When i remove "use strict" it returns nothing.Please help me out

<code>
#!/usr/bin/perl
use strict;
use warnings;
print `grep abc /home/test/file.txt|perl -lane 'print \"$F[0] $F[1] $F[2]\"' > a.txt`;
</code>
Why do you invoke a Perl one-liner from within a Perl program ??

Code:
#!/usr/bin/perl
use strict;
use warnings;
my $file = "/home/test/file.txt";
my @x;
open (F, "<", $file) or die "Can't open $file: $!";
while (<F>) {
  chomp;
  if (/abc/) {
    @x = split;
    print "$x[0] $x[1] $x[2]\n";
  }
}
close(F) or die "Can't close $file: $!";

tyler_durden
# 3  
Old 11-25-2010
Hi,

Another solution:
Code:
$ perl -lane 'print(@F[0..2]) if grep(/abc/, $_)' file.txt

Regards,
Birei
# 4  
Old 11-29-2010
Birei,
It works when i put this is unix prompt but its not working inside a perl script,


Code:
#!/usr/bin/perl
use strict;
use warnings;
print `perl -lane 'print(@F[0..2]) if grep(/abc/, $_)' /home/test/file.txt > a.txt`;;


<error>
Possible unintended interpolation of @F in string at ./new.pl line 17.
Global symbol "@F" requires explicit package name at ./new.pl line 17.
</error>

Reason i am putting in script is, i have to process like this for different columns also inside a main foreach loop. This loop goes line by line in that file.txt.
Please help me to make this one-liner to work inside the perl script. Thanks.

Regards,
Prabhu
Last edited by DukeNuke2; 11-30-2010 at 05:21 AM..
# 5  
Old 11-30-2010
Hi,

I think my last script has an error, it should be like this:
Code:
 $ perl -lane '$,=" "; print(@F[0..2]) if grep(/abc/, $_)' file.txt

Here you have the script, test it:
Code:
$ cat script.pl
#!/usr/bin/perl
use warnings;
use strict;

$,=" ";
while (<>) {
    chomp;
    my @fields = split;
    print(@fields[0..($#fields>2?2:$#fields)], "\n") if grep(/abc/, $_);
}
$ ./script.pl file.txt
$ ## (Output supressed).

Regards,
Birei
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