sed question for search and replace
 

I'm running into a problem where I don't see what I'm doing wrong. I have a line in a config file (it will always be line 38, FWIW):
$rcmail_config['default_host'] = '';

That I want to replace with:

$rcmail_config['default_host'] = 'localhost';

No problem. Trusty sed should get the job done, right?

sed -e 's/$rcmail_config[\'default_host\'] = \'\';/$rcmail_config[\'default_host\'] = \'localhost\';/g' main.config

But I think I have my escapes wrong somewhere.
Can someone tell me where I messed up?
Thanks in advance.

It might be because of this: The poorly undocumented ;

HTH,

Centinul

I'm sure it's because I'm not escaping something in there.... SO I tried this:

sed -e 's/$rcmail_config[\'default_host\'] = \'\'\;/$rcmail_config[\'default_host\'] = \'localhost\'\;/g' main.config

And that gives me a line like it's waiting for something else.

Hi,

If the line is always on line 38:

sed "38s/'';$/'localhost';/" infile

If it's not:

sed "s/\$rcmail_config\['default_host'\] = '';$/\$rcmail_config['default_host'] = 'localhost';/" infile

Hope this helps.

Druuna
Are you able to write those sed commands without looking at a book or some other material?
I know you are clever.
I must look at a book or online material to write sed and awk commands.

Grr.... Neither of those work either.
And yes, it will always be on line 38.
This did work, though:

perl -pi -e "s/''/'localhost'/" main.inc.php.dist

Thanks for all the help. The double quotes got me bumped in the right direction!

Hi,

perl, where did that come from? You asked for a sed solution ;)

Maybe you just settled for perl. It's strange that the two examples given don't seem to work (you remember what went wrong?). I just tried both of them and here they do what they are supposed to do.

But, you have a working solution, thats all that matters in the end :)

@Gins: By now I don't need books/the net for this, but that's experience.

EDIT
@jakev383: You do know that the " after sed and before infile are double qoutes, not 2 single quotes? The '' after the / and before the ; are 2 single quotes.
/EDIT

Druuna
When it comes to sed and awk, there are hundreds or rather thousands of commands. You should be a genius to know everything by heart. I am an idiot.

When it comes to 'grep' commands, there is a limit. I may be wrong.

Where did perl come from? Once thing I've learned in Linux - it doesn't matter what you do or how you do it, as long as 2+2=4 in the end. If nothing else I think it's safe to say there's at least 3 ways of doing anything in Linux.
That being said, when I was doing a search-n-replace sed popped in my head. I couldn't get it to do what I wanted and after Gins bumped me with those double quotes, well, sed still didn't work but I thought "why not try perl?" since I was using it 5 lines prior in my little script anyway.
And yeah, I don't know why those don't work either. I ran them on a Cent4.4 machine which shouldn't matter but I've seen some weird things on Debian distros where /bin/sh wasn't linked to /bin/bash so scripts did funny things sometimes.
Thanks everyone!