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# 1  
Old 02-27-2012
Perl: Conditional replace based on previous and current value in a line
I need to read the contents of a file. Then I need to grep for a keyword and replace part of the grepped line based on the condition of previous and present line.


Example input file:
Code:
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0; /* if next shift_port is P0 I need to replace this with M0; and next shift_port's P0; with 00;
    port3       = 0;
    reset       = 1;
   }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0;
    port3       = 0;
    reset       = 1;
   }
  Macro "Inputs" { 
    test_ip =
        110111010110
  }

  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = 00;
    port3       = 0;
    reset       = 1;
  }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = 00; 
    port3       = 0;
    reset       = 1;
   }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0;/* if next shift_port is P0; I need to replace this with M0; and next shift_port's P0 with 00;
    port3       = 0;
    reset       = 1;
   }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0;/* if next shift_port is P0; I need to replace this with M0; and next shift_port's P0 with 00;
    port3       = 0;
    reset       = 1;
   }
}

Desired output file
Code:
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = M0; /* if next shift_port is P0; I need to replace this with M0; and next shift_port's P0 with 00;
    port3       = 0;
    reset       = 1;
   }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = 00;
    port3       = 0;
    reset       = 1;
   }
  Macro "Inputs" { 
    test_ip =
        110111010110
  }

  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = 00;
    port3       = 0;
    reset       = 1;
  }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = 00; 
    port3       = 0;
    reset       = 1;
   }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = M0;/* if next shift_port is P0; I need to replace this with M0; and next shift_port's P0 with 00;
    port3       = 0;
    reset       = 1;
   }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = 00;/* if next shift_port is P0; I need to replace this with M0; and next shift_port's P0 with 00;
    port3       = 0;
    reset       = 1;
   }
}

I am trying to use a perl script to implement this.

Thanks in advance for your help

---------- Post updated at 08:03 AM ---------- Previous update was at 07:59 AM ----------

I am able to display the line that have 2 P0; with the following piece of code. But I need to write the output to a separate file


Code:
#!/tool/pandora/bin/perl5.10.0 
use strict;
my $count = 0;
open(INFILE, "<$ARGV[0]");
my @data_in_file = <INFILE>;
close (INFILE);
my @shifts = grep { /shift_port = / } @data_in_file;
foreach my $line (@shifts) 
{
	if ($line=~m/shift_port = P0;/) 
	{
		  $count++;
		 print "$count\n";	
		if ($count == 2)
			{
			print "found 2 P0\n";
			$count = 0;
			}
	} else {
		$count = 0;
	}

}

# 2  
Old 02-27-2012
Hi naveen@,

I don't understand your perl script. It outputs nothing with that input file, and I think you didin't match the exact withespace.

Try next one:
Code:
$ cat infile
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0; /* if next shift_port is P0 I need to replace this with M0; and next shift_port's P0; with 00;
    port3       = 0;
    reset       = 1;
   }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0;
    port3       = 0;
    reset       = 1;
   }
  Macro "Inputs" { 
    test_ip =
        110111010110
  }

  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = 00;
    port3       = 0;
    reset       = 1;
  }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = 00; 
    port3       = 0;
    reset       = 1;
   }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0;/* if next shift_port is P0; I need to replace this with M0; and next shift_port's P0 with 00;
    port3       = 0;
    reset       = 1;
   }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0;/* if next shift_port is P0; I need to replace this with M0; and next shift_port's P0 with 00;
    port3       = 0;
    reset       = 1;
   }
}
$ cat script.pl
use warnings;
use strict;

die qq[Usage: perl $0 <input-file>\n] unless @ARGV == 1;

my @range_lines = ();

while ( <> ) {
        chomp;
        if ( m/\A\s*(?i:shift_port)\s*=/ ... m/\A\s*(?i:shift_port)\s*=/ ) {
                push @range_lines, $_;
                next;
        }

        if ( @range_lines ) {
                if ( $range_lines[0] =~ m/=\s*P0\s*;/ &&
                         $range_lines[ $#range_lines ] =~ m//
                ) {
                        $range_lines[0] =~ s/P0/M0/;
                        $range_lines[ $#range_lines ] =~ s/P0/00/;
                }

                printf qq[%s\n], join qq[\n], splice @range_lines;
        }

        printf qq[%s\n], $_;
}
$ perl script.pl infile
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = M0; /* if next shift_port is P0 I need to replace this with M0; and next shift_port's P0; with 00;
    port3       = 0;
    reset       = 1;
   }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = 00;
    port3       = 0;
    reset       = 1;
   }
  Macro "Inputs" { 
    test_ip =
        110111010110
  }

  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = 00;
    port3       = 0;
    reset       = 1;
  }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = 00; 
    port3       = 0;
    reset       = 1;
   }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = M0;/* if next shift_port is P0; I need to replace this with M0; and next shift_port's P0 with 00;
    port3       = 0;
    reset       = 1;
   }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = 00;/* if next shift_port is P0; I need to replace this with M0; and next shift_port's P0 with 00;
    port3       = 0;
    reset       = 1;
   }
}

Regards,
Birei
This User Gave Thanks to birei For This Post:
naveen@
# 3  
Old 02-27-2012
Hi Birei,

I need another small improvement in the code

Say the input file is the one below. I need to replace 1st P0 with M0 and second with 00 if and only if the value of port3 is not 1 on both V{}

Input file

Code:
V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0; 
    port3       = 1; /* port 3 is 1 . So dont replace this even if next shift port is P0 */
    reset       = 1;
   }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0; /* port 3 is 0 and current shift_port is P0. If port 3 is 0 in next v{} and shift_port is P0 then replace this with M0 and next shift port with 00 */
    port3       = 0;
    reset       = 1;
   }

 W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0;
    port3       = 0;
    reset       = 1;
   }

  Macro "Inputs" { 
    test_ip =
        110111010110
  }

  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0;
    port3       = 1; /* port 3 is 1 . So dont replace this even if next shift port is P0 */
    reset       = 1;
  }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = 00; 
    port3       = 1;
    reset       = 1;
   }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0;
    port3       = 1;  /* port 3 is 1 . So dont replace this even if next shift port is P0 */
    reset       = 1;
   }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0; /* port 3 is 0 and current shift_port is P0. If port 3 is 0 in next v{} and shift_port is P0 then replace this with M0 and next shift port with 00 */
    port3       = 0;
    reset       = 1;
   }
 W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0; 
    port3       = 0;
    reset       = 1;
   }
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0;
    port3       = 1;  /* port 3 is 1 . So dont replace this even if next shift port is P0 */
    reset       = 1;
   }
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0;
    port3       = 1;  /* port 3 is 1 . So dont replace this even if next shift port is P0 */
    reset       = 1;
   }
}

Required output

Code:
V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0; 
    port3       = 1; /* port 3 is 1 . So dont replace this even if next shift port is P0 */
    reset       = 1;
   }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = M0; /* port 3 is 0 and current shift_port is P0. If port 3 is 0 in next v{} and shift_port is P0 then replace this with M0 and next shift port with 00 */
    port3       = 0;
    reset       = 1;
   }

 W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = 00;
    port3       = 0;
    reset       = 1;
   }

  Macro "Inputs" { 
    test_ip =
        110111010110
  }

  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0;
    port3       = 1; /* port 3 is 1 . So dont replace this even if next shift port is P0 */
    reset       = 1;
  }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = 00; 
    port3       = 1;
    reset       = 1;
   }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0;
    port3       = 1;  /* port 3 is 1 . So dont replace this even if next shift port is P0 */
    reset       = 1;
   }
  W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = M0; /* port 3 is 0 and current shift_port is P0. If port 3 is 0 in next v{} and shift_port is P0 then replace this with M0 and next shift port with 00 */
    port3       = 0;
    reset       = 1;
   }
 W wf_cyc;
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = 00; 
    port3       = 0;
    reset       = 1;
   }
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0;
    port3       = 1;  /* port 3 is 1 . So dont replace this even if next shift port is P0 */
    reset       = 1;
   }
  V { 
    port1       = P;
    port2       = 0;
    shift_port  = P0;
    port3       = 1;  /* port 3 is 1 . So dont replace this even if next shift port is P0 */
    reset       = 1;
   }
}

Last edited by naveen@; 02-28-2012 at 11:48 AM.. Reason: clear explanation
# 4  
Old 02-28-2012
Why didn't you post that input file in your first message? And why didn't you tell us all your requirements at once? Because probably that doesn't involve an improvement in the code, but to redo it with other approach. Take it as an advice, but you will find more help if work like that.

Quote:
Say the input file is the one below. I need to replace 1st P0 with M0 and second with 00 if and only if the value of port is 1 on both V{}
What does it mean? I don't see any 'port' value in your input file.
# 5  
Old 02-28-2012
Sorry about the lack of clarity and also not specifying the requirements upfront. I edited the improvement requested above to make it clear.
Thanks in advance for your help
# 6  
Old 02-28-2012
Why do you have two threads about the same topic? crossposting is against the rules.
# 7  
Old 02-28-2012
I wanted a perl and shell script. So you were helping me with awk and Birei was with perl. So i didnt delete the duplicate post. Initially I didnt know which category I should have posted. sorry about that
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