if match found go to a particular line in perl

user_prady · #1 (**permalink**) 03-27-2008

Hello Experts,

I am newbie to perl, just curious to know how to do the following in perl.
suppose I ve a txt file like below. when it founds "*Main Start"
Then go to "*Main End,,,,,,,," patteren and just collect the number from the previous line of "*Main End,,,,,,," pattern . In my case it is 5 . Then start excuting normally from the "*Main Start" position

Following is the picture .. I dont want to create any temp file also..
Input file:

Code:

*Init End
*Main Start
*Comment Reset Timers
000000,0000,0,0,0,0,0,1,0
000000,0000,0,0,0,0,1,1,0 
*Comment Control Frame at 1.04596 ms
000000,0400,0,0,0,0,1,0,1
2418A4,0000,0,1,3,0,0,0,0 
049C00,0000,0,0,2,0,0,0,0
*Comment Control Frame at 1.04673 ms
*Comment Control Frame at
000002,0000,0,0,0,0,1,0,1
241002,0000,0,1,3,0,0,0,0
000100,0000,0,0,2,0,0,0,0
*Comment Control Frame at
000004,0000,0,0,0,0,1,0,1
241002,0000,0,1,3,0,0,0,0
000000,0000,0,0,2,0,0,0,0
*Comment Frame 13 at ** us,,,,,,,,
000005,7E3D,0,0,0,0,1,0,1
*Main End,,,,,,,,

output:

Code:

*Init End
*Main Start
 repeat(5);
process all lines as usual here.

............
*Main End,,,,,,,,,

I ve to print all lines as it is when it found a line starting with * . Thats why I am doing like below

Code:

 if(m/^\*/){
              print "//", $_;
              next;
    }

Code:

Basic Algorithm of my programme need :
1. If "*Main Start" pattern found go to line where Pattern matches "*Main end".
2. Get the previous line. and get the value of the first field.
3. Return to "*Main start" position again. & Print repeat(that number) : in my case it is 5 :
4. stop/next;

Any help most appriciated..

regards,
user_prady

user_prady · #2 (**permalink**) 03-30-2008

Quote:

Originally Posted by user_prady

Hello Experts,

I am newbie to perl, just curious to know how to do the following in perl.
suppose I ve a txt file like below. when it founds "*Main Start"
Then go to "*Main End,,,,,,,," patteren and just collect the number from the previous line of "*Main End,,,,,,," pattern . In my case it is 5 . Then start excuting normally from the "*Main Start" position

Following is the picture .. I dont want to create any temp file also..
Input file:

Code:

*Init End
*Main Start
*Comment Reset Timers
000000,0000,0,0,0,0,0,1,0
000000,0000,0,0,0,0,1,1,0 
*Comment Control Frame at 1.04596 ms
000000,0400,0,0,0,0,1,0,1
2418A4,0000,0,1,3,0,0,0,0 
049C00,0000,0,0,2,0,0,0,0
*Comment Control Frame at 1.04673 ms
*Comment Control Frame at
000002,0000,0,0,0,0,1,0,1
241002,0000,0,1,3,0,0,0,0
000100,0000,0,0,2,0,0,0,0
*Comment Control Frame at
000004,0000,0,0,0,0,1,0,1
241002,0000,0,1,3,0,0,0,0
000000,0000,0,0,2,0,0,0,0
*Comment Frame 13 at ** us,,,,,,,,
000005,7E3D,0,0,0,0,1,0,1
*Main End,,,,,,,,

output:

Code:

*Init End
*Main Start
 repeat(5);
process all lines as usual here.

............
*Main End,,,,,,,,,

I ve to print all lines as it is when it found a line starting with * . Thats why I am doing like below

Code:

 if(m/^\*/){
              print "//", $_;
              next;
    }

Code:

Basic Algorithm of my programme need :
1. If "*Main Start" pattern found go to line where Pattern matches "*Main end".
2. Get the previous line. and get the value of the first field.
3. Return to "*Main start" position again. & Print repeat(that number) : in my case it is 5 :
4. stop/next;

Any help most appriciated..

regards,
user_prady

Hi friends is there anyway to do it. Pls help ..

Thanks

era · #3 (**permalink**) 03-30-2008

Don't depend on me, I need to be going back to my day job soon.

There's a number of ways to do this, obviously. The old-fashioned variant would be to remember the previous line and print that when you see the terminator. The really brute Perl approach would be to slurp the whole file and substitute everything with an empty string except the line before the terminator. There's one in the Perl FAQ about that; perlfaq6 and scroll around for related questions. (The question about C comments further down the page has some hints, too.)

But the "previous line" solution is absolutely the simplest in this case, if you have no further requirements.

Code:

perl -ne 'BEGIN { $matching = 0; }
  $matching = 1 if (m/^\*Main Start/);
  next unless $matching;
  print $prev if (defined $prev && m/^\*Main End/);
  $prev = $_'

Not sure about the flow control you tried to describe. Are you supposed to remember everything from main start until main end and print that after the output from the last line before main end? (I guess this already qualifies as a pseudo-code implementation of what it takes. But then maybe I would consider a regex substitution over the whole file, or each *Main Start section, after all.)

user_prady · #4 (**permalink**) 03-30-2008

Quote:

Originally Posted by era

Don't depend on me, I need to be going back to my day job soon.

There's a number of ways to do this, obviously. The old-fashioned variant would be to remember the previous line and print that when you see the terminator. The really brute Perl approach would be to slurp the whole file and substitute everything with an empty string except the line before the terminator. There's one in the Perl FAQ about that; perlfaq6 and scroll around for related questions. (The question about C comments further down the page has some hints, too.)

But the "previous line" solution is absolutely the simplest in this case, if you have no further requirements.

Code:

perl -ne 'BEGIN { $matching = 0; }
  $matching = 1 if (m/^\*Main Start/);
  next unless $matching;
  print $prev if (defined $prev && m/^\*Main End/);
  $prev = $_'

Not sure about the flow control you tried to describe. Are you supposed to remember everything from main start until main end and print that after the output from the last line before main end? (I guess this already qualifies as a pseudo-code implementation of what it takes. But then maybe I would consider a regex substitution over the whole file, or each *Main Start section, after all.)

Thanks a Lot Era for your kindness..I ll try your mentioned way..

era · #5 (**permalink**) 03-30-2008

I don't think I have captured all your requirements correctly but at least it's a start. If I am allowed to guess, what would be easiest is collect the output in a variable and print it after you have seen *Main End and printed out the line which immediately preceded it.

user_prady · #6 (**permalink**) 03-31-2008

Quote:

Originally Posted by era

I don't think I have captured all your requirements correctly but at least it's a start. If I am allowed to guess, what would be easiest is collect the output in a variable and print it after you have seen *Main End and printed out the line which immediately preceded it.

I tried almost all way using next , redo and last command in perl , But I can't get these syntax correctly in perl. I know its easy ,but still I cant find the efficient way using while and next statement in perl.

I am trying to do the follwoing in perl

Code:

nawk ' {
        if($0 ~ /^\*Main Start/){
	     while( $0 !~ /^\*Main End/){
	     print $0;
             getline;
        }
     }
 } ' my.txt

One more code I want to do it in perl pls give me some basic idea how to do it without creating any temporary files ..

Code:


TMP=/tmp/my_tmp$$
nawk '
/\*Main End/{
split(x,arr,",")
print "Loop  " arr[1]
};
{x=$0
}
' my.txt > $TMP 

nawk '{
if($0 ~ /^Loop/){
    loop = $2 
    next;
  }
if($0 ~ /^\*Main Start/){
     printf "\nrepeat ("
     print  loop

} ' $TMP $my.txt

Thanks & Regards,
user_prady

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