How to replace one character inside parentheses keep everything else as is

Question

The data looks like this :

There is stuff here (word, word number phrases)
(word number anything, word phrases), even more
...

There is a lot of them in different files. There is different kind of data too, all around it that isn't in the same format. The data inside the paratheses can't change, and it's always on the same line. I do not have to deal with:

(stuff number,
maybe more here)

I would like to be able to replace the comma with a colon

Desired output would be

There is stuff here (word: word number phrases)
(word number anything: word phrases), even more
...

Answer 1

Here's a version for awk that uses the parentheses as record separators:

awk -v RS='[()]' 'NR%2 == 0 {sub(/,/,":")} {printf "%s%s", $0, RT}' file

The stuff between parentheses will be every even-numbered record. The RT variable holds the character that matched the RS pattern for this record.

Note that this only replace the first comma of the parenthesized text. If you want to replace all, use gsub in place of sub

Answer 2

Assuming there's only one comma to be replaced inside parentheses, this POSIX BRE sed expression will replace it with colon:

sed 's/(\(.*\),\(.*\))/(\1:\2)/g' file

If there are more than one comma, only the last one will be replaced.

In multiple-commas scenario, you can replace only the first one with:

sed 's/(\([^,]*\),\([^)]*\))/(\1:\2)/g' file