[SOLVED] substitute ( in sed

ghantauke · 03-11-2011, 04:29 AM

I want to substitute every occurance of "( S" to "(S" in my file (the quotes aren't included in my file. Its just there to specify what my pattern is)

This is my attempt to do it and the error message I get.

Code:

denish@ubuntu:~/Desktop/tgrep files$ sed 's/^\( \(S$/\(S/g' test > test2
sed: -e expression #1, char 16: Unmatched ( or \(

The "\( \)" has a different purpose in sed. So how exactly do I specify a ( in sed as a pattern and not as the special function?

colucix · 03-11-2011, 04:33 AM

To take it literally, enclose the parenthesis in a character list:

Code:

sed 's/[(] S/(S/g' test

corp769 · 03-11-2011, 04:33 AM

You need to use ^( in the search field of said, not \(

Edit - colucix beat me to it. You can also do it his way.

sycamorex · 03-11-2011, 04:34 AM

What about:

Code:

sed 's/( S/(S/g' file

colucix · 03-11-2011, 04:37 AM

Or eventually use the -r option and escape the parenthesis. In extended regular expression mode, sed will recognize plain parentheses as the symbols to enclose a pattern to keep, whereas the escaped one will be a literal parenthesis:

Code:

sed -r 's/\( S/(S/g' test

Edit: sycamorex's simple and direct solution works for me. Indeed it's the opposite of what I have just explained: in normal mode the plain parenthesis will be literal.

sycamorex · 03-11-2011, 04:38 AM

Quote:

Originally Posted by colucix

To take it literally, enclose the parenthesis in a character list:

Code:

sed 's/[(] S/(S/g' test

Is it absolutely necessary? Plain:

Code:

sed 's/^( S/(S/' infile

seems to work as well.

corp769 · 03-11-2011, 04:39 AM

^( always worked for me...

ghantauke · 03-11-2011, 10:46 AM

Thanks for the help. I was just being silly. ( isn't a special character to there's no need for \ infront of it. I tired doing it without the \ before posting but I messed up the syntax so I thought none of those method work. Again thanks for all your help.