how to use find and replce command in perl script

ckchelladurai · 06-15-2011, 02:37 AM

Hi, I have one perl sctipt which generate cfg file with ^M in all the EOL. I need to remove the ^M from the cfg file. How can i remove that from the perl script itself.

I have tried the following unix command in perl script,
system("perl -pi -e 's/^M//g' *.cfg");

It doesn't work.
Could you please help on this....

Thanks,
Chella...

Snark1994 · 06-15-2011, 03:25 AM

Code:

system("perl -pi -e 's/\r\n/\n/g' *.cfg");

A "better" (read as 'without using the system() call') solution would be:

Code:

@files = <*.cfg>;
foreach $filename (@files) {
    if(-f $filename && -r $filename && -w $filename){
        rename("$filename","$filename.bak");
        open INPUT, "$filename.bak";
        open OUTPUT, ">$filename";
        while( <INPUT> ) {
            s/\r\n$/\n/;
            print OUTPUT $_;
        }
        close INPUT;
        close OUTPUT;
        unlink("$filename.bak");
    }
}

It's creating it in DOS format, sounds like. Though an even better solution would be to change the first script, and make sure it only outputs the '\n', not the '\r' as well.

ckchelladurai · 06-15-2011, 07:21 AM

Hi,
Thanks for your reply. Will i use this perl code in end of my existing perl code???
I am very new to the perl script.. :-(

Snark1994 · 06-16-2011, 10:26 AM

It should work if you put it where you had the "system()" line. You may have to use 'my @files;' and 'my $filename;' to avoid errors.

However, I only really posted the script to show that you don't need the system call. Like I said, the best way to fix it is to read through the first perl script (which creates the .cfg files), and change where it tries to print '\r\n' to only printing '\n'

Note: If you're running Windows (which your OS icon suggests) then using '\r\n' as a line ending is the default. In which case, perhaps you could use a different editor that supports both Unix and DOS line endings (such as vim)

chrism01 · 06-16-2011, 08:53 PM

Alternately, there's always the dos2unix util.
http://linux.die.net/man/1/dos2unix

Noway2 · 06-17-2011, 04:41 AM

Quote:

system("perl -pi -e 's/^M//g' *.cfg");

I have used perl to remove the ^M (control-M) characters at the end of the line. Sed would work too, as might grep with the output passed to another file.

I think the problem is in your regular expression. In regular expressions, ^ is start of the line, not the control key. This means your script is trying to find lines that start with the letter M and erase the M character. Not quite what you want.
I believe what you want is to use the \cM where the \c is an escape sequence representing the control key. Try this instead.

Code:

system("perl -pi -e 's/\cM//g' *.cfg");