PERL one-liner help needed (text search and replace)

[Mel Burslan]

Since I have never got to master perl, I am lost here. So I will not even make an attempt at this one liner

All I want from this one liner is to replace a portion of a line in a given file. To be more specific, I need to disable the prm daemon on 50+ servers. To do this, I need to change the the line

PRM_RMTCONF=1

to

PRM_RMTCONF=0

So, what I am expecting from this one-liner is to look for the line, containing PRM_RMTCONF string and replce the value after the "=" to 0 (zero) regardless if it is 1 or 0 in the file /etc/rc/config.d/prm

It needs to be a one-liner because I want to launch it from a trusted management server via ssh and run it in a command line using a non-interactive session.

I know perl is created situations like this but I do not know how to attack this problem.

Help is greatly appreciated.

[James R. Ferguson · Accepted solution]

Hi Mel:

# perl -pi.old e 's/PRM_RMTCONF=\d\b/PRM_RMTCONF=0/' file

...This will substitute PRM_RMTCONF= with PRM_RMTCONF=0. The old version of the input file will be retained as "file.old" and the new editted version remain as "file". This is an inplace update.

Regards!

...JRF...

[A. Clay Stephenson]

It's very easy using -i and -p.

perl -p -i -e 's/PRM_RMTCONF=1/PRM_RMTCONF=0/' myfile

This will modify "myfile" in place.

If you like you can add an argment to the -i switch:

perl -p -i.old -e 's/PRM_RMTCONF=1/PRM_RMTCONF=0/' myfile

and this has the effect of making a backup file myfile.old while the modified file, myfile, is rewritten.

[James R. Ferguson]

Hi (again() Mel:

Ooops! I dropped the "-" in fron of the "-p" switch:

# perl -pi.old -e 's/PRM_RMTCONF=\d\b/PRM_RMTCONF=0/' file

Regards!

...JRF...

[Sandman!]

imho...here's an ex solution in case you're interested:

# ex -s +"/^PRM_RMTCONF=/s/[0-9]*$/0/ | wq" /etc/rc.config.d/prm

[Mel Burslan]

Thanks for all of the responses. PERL one-liners worked like charm.