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Perl: Conditional replace based on previous and current value in a line

 
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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;
	}

}

 
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