regular expression (.*?)

uttam_h · 05-30-2008, 07:01 AM

hi all,
i have a text file with below content

...............................
...............................
...............................
...............................
%%Page: (4) 4
%%PageBoundingBox: 34 -30 584 831
%%BeginPageSetup
%%BeginFeature: *PageSize A4
595 842 SetPageSize
%%EndFeature
%%BeginFeature: *Duplex None
false false SetDuplexMode
%%EndFeature
%%EndPageSetup
GS
.........................
................................
..........................................

i want to add some lines after GS so in perl i tried this

$data = ~s/%%Page: (4) 4(.*?)GS/%%Page: (4) 4 $1 GS setlinewidth \n 25 110 moveto \n 75 110 lineto/g;

where $data holds file content. this is working fine and the output is

...............................
...............................
...............................
...............................
%%Page: (4) 4
%%PageBoundingBox: 34 -30 584 831
%%BeginPageSetup
%%BeginFeature: *PageSize A4
595 842 SetPageSize
%%EndFeature
%%BeginFeature: *Duplex None
false false SetDuplexMode
%%EndFeature
%%EndPageSetup
GS
setlinewidth
25 110 moveto
75 110 lineto
.........................
................................
..........................................

but when i tried this with perl command line it is not working

perl -p -i -e 's/%%Page: (4) 4(.*?)GS/%%Page: (4) 4 $1 GS setlinewidth \n 25 110 moveto \n 75 110 lineto/g' FILENAME

Kindly suggest me the solution(in sed/awk/perl etc)

Thanks in advance

uttam hoode

druuna · 05-30-2008, 09:30 AM

Hi,

Would this help:

sed 's/^GS/GS\nsetlinewidth\n25 110 moveto\n75 110 lineto/' text.file.with.below.content

Sample run:

Code:

sed 's/^GS/GS\nsetlinewidth\n25 110 moveto\n75 110 lineto/' infile
...............................
...............................
...............................
...............................
%%Page: (4) 4
%%PageBoundingBox: 34 -30 584 831
%%BeginPageSetup
%%BeginFeature: *PageSize A4
595 842 SetPageSize
%%EndFeature
%%BeginFeature: *Duplex None
false false SetDuplexMode
%%EndFeature
%%EndPageSetup
GS
setlinewidth
25 110 moveto
75 110 lineto
.........................
................................
..........................................

Hope this helps.

osor · 05-30-2008, 01:36 PM

The problem with the original is that you end up reading line by line, so you never get the entire preamble. Solutions include:

Match only the relevant portion of the last line as druuna suggested.
Read the file either in slurp mode or in paragraph mode (see perldoc perlrun and the -0 flag).

matthewg42 · 05-30-2008, 01:52 PM

An ugly, but working solution is to iterate over the lines of the file and set a flag when you're on the right page, and only test for the GS line when you know you're on the right page. e.g.

Code:

#!/usr/bin/perl

use strict;

my $do_replace = 0;
my $text_to_insert = "setlinewidth 25 110\nmoveto 75 110 lineto";

while(<>)
{
    if (/^%%Page: \(4\) 4/) { $do_replace = 1; }

    if ($do_replace)
    {
        if (s/GS/GS\n$text_to_insert/) { $do_replace = 0; }
    }

    print;
}

Telemachos · 05-30-2008, 05:00 PM

If the file looks the way you describe it, why not this one liner?

Code:

perl -i.bak -pe 's/^GS$/GS\nsetlinewidth\n25 110 moveto\n75 110 lineto/' file-name

It works just fine in a test here.

matthewg42 · 05-30-2008, 05:42 PM

Quote:

Originally Posted by Telemachos

If the file looks the way you describe it, why not this one liner?

Code:

perl -i.bak -pe 's/^GS$/GS\nsetlinewidth\n25 110 moveto\n75 110 lineto/' file-name

It works just fine in a test here.

But it doesn't work when there are multiple pages and the requirement is to alter only some specific page - it alters all pages.

matthewg42 · 05-30-2008, 05:45 PM

Here's a one-liner with sed which modifies only one page:

Code:

sed '/^%%Page: (4)/,/^%%Page: / s/GS/GS\nsetlinewidth 25 110\nmoveto 75 110 lineto/' test.ps > test_modified.ps