trying to find and replace a string using perl

Question

in perl, I am trying to open a file , find a string, replace the string, and close the file. I have scoured the internet, and this is what I have come up with:

  #!/usr/bin/perl -w
  #  use warnings;  

    my $oldUrl = "someString";
    my $newUrl = "someOtherString";
    $file = "someFile";
    open (MYFILE,"$file") or die "Can't open '$file': $!";
    while(my $row = <MYFILE>){
            if($row =~ /$oldUrl/)
            {
                    $row = "$newUrl";
                    print MYFILE $row;
            }
    }
    close(MYFILE);

this does nothing except print to screen the text: someString. I cant get the newUrl to get actually written in the file, what am i missing?

how would i do all files in a dir that end in .cfg:

  #!/usr/bin/perl -w
use warnings;

my $directory = '/tftpboot';

my $oldUrl = "account.1.sip_server_host = s150133.trixbox.fonality.com";
my $newUrl = "account.1.sip_server_host = 162.221.24.130";
 ....
  .....

open(FOO, $file) opens $file for reading, but you're also trying to write to it. That won't work. Also, this won't fix your particular issue, but in general, you should use the safer, three-argument form of open and lexical filehandles: open my $fh, '<', $file or die $!; — ThisSuitIsBlackNot
– ThisSuitIsBlackNot, Commented Aug 18, 2014 at 21:25

Miller · Accepted Answer · 2014-08-18 21:28:04Z

3

Please read: perlfaq5 - How do I change, delete, or insert a line in a file, or append to the beginning of a file?

I would recommend using $INPLACE_EDIT to handle the opening and closing of the file for you. However, other methods are listed in the above reference:

#!/usr/bin/perl
use strict;
use warnings;
use autodie;

my $file = "someFile";
my $oldUrl = "someString";
my $newUrl = "someOtherString";

local @ARGV = $file;
local $^I = '.bak';
while (<>) {
    s/.*$oldUrl.*/$newUrl/;   # Replacing the whole line seems odd, but it's what you did in your example.
    print;
}
#unlink "$file$^I"; #Optionally delete backup

edited Aug 18, 2014 at 21:28

answered Aug 18, 2014 at 21:19

Miller

35.3k4 gold badges42 silver badges61 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

jaypal singh Over a year ago

Typically sed would have barfed on those delimiters if the variables contained the delimiter characters. Odd that perl didn't complain.

bart2puck Over a year ago

Miller. how would i do this with a whole directory? see edit.

Miller Over a year ago

To process an entire directory, you simply need to load it using opendir and readdir, and remember to specify the full path information when attempting to modify the file. Alternatively, you could use a module like Path::Class to work in a more platform independent way.

jh314 · Accepted Answer · 2014-08-18 21:12:09Z

1

You can use this one-liner to replace string in a file:

perl -pi.bak -e 's/someString/someOtherString/g' someFile

answered Aug 18, 2014 at 21:12

jh314

27.9k16 gold badges66 silver badges83 bronze badges

2 Comments

bart2puck Over a year ago

Yea, the only problem is I need to loop through a bunch of files.. So I think it needs to be a script?

jh314 Over a year ago

instead of someFile, you can also use *.txt

Collectives™ on Stack Overflow

trying to find and replace a string using perl

2 Answers 2

3 Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related