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Xplorer4x4 09-29-2012 07:35 PM
Trouble using sed
 
I need to replace 127.0.0.1 on line 49 with an *

I tried:
Code:
sed '49s/127.0.0.1/*/'
No luck. I tried some variations using double quotes and such with no luck.

amboxer21 09-29-2012 07:42 PM
Try this

Code:
sed -e '49s/127.0.0.1/*/g' filename.txt

billyoc 09-29-2012 08:05 PM
Quote:
Originally Posted by amboxer21 (Post 4792875)
Code:
sed -e '49s/127.0.0.1/*/g' filename.txt
I'm using a bash shell btw.
I can't reproduce the problem, what you have works here.

GNU bash, version 4.2.10(1)-release (i686-pc-linux-gnu)
GNU sed version 4.2.1

Xplorer4x4 09-29-2012 08:14 PM
Quote:
Originally Posted by amboxer21 (Post 4792875)
Code:
sed -e '49s/127.0.0.1/*/g' filename.txt
I'm using a bash shell btw.
I am using a bash shell on a ubuntu server. I tested this and I see it print the entire script and it shows me the change but when I review the file manually in nano, 127.0.0.1 is still in the file. For what it is worth, the entire line is
Code:
"rpc-whitelist": "127.0.0.1",

amboxer21 09-29-2012 08:29 PM
Quote:
Originally Posted by Xplorer4x4 (Post 4792899)
I am using a bash shell on a ubuntu server. I tested this and I see it print the entire script and it shows me the change but when I review the file manually in nano, 127.0.0.1 is still in the file. For what it is worth, the entire line is
Code:
"rpc-whitelist": "127.0.0.1",
It's because your not writing the changes to file. It wouldn't make a difference though. Sed is searching for the string 127.0.0.1 and replacing it with an asterisk. So the text before it doesn't matter.

amboxer21 09-29-2012 08:32 PM
Use the -i switch if you want to apply changes to the same file

Code:
sed -i '49s/127.0.0.1/*/g' filename.txt

Xplorer4x4 09-29-2012 08:35 PM
As I said in the OP, I needed to replace a lin so I tried the -i switch and it worked great! Thanks for the quick response!

David the H. 09-30-2012 11:19 AM
It's cleaner to use the [c]hange command instead of the [s]ubstitution command here.

Code:
sed -i '49c*' file.txt
Here are a few useful sed references:
http://www.grymoire.com/Unix/Sed.html
http://sed.sourceforge.net/grabbag/
http://sed.sourceforge.net/sedfaq.html
http://sed.sourceforge.net/sed1line.txt


Another option that I like to use is ed. As a true text editor it's more flexible in many circumstances. But it can also be a bit more hassle to set up.

Code:
ed -s file.txt <<<$'49c\n*\n.\nw'
How to use ed:
http://wiki.bash-hackers.org/howto/edit-ed
http://snap.nlc.dcccd.edu/learn/nlc/ed.html
(also read the info page)


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