Using sed to replace between a specific pattern I've been trying with `sed`, and googling for the whole morning, and I can't seem to get this to work. Is it possible with `sed` to **lowercase** text between two specific characters: i.e. SOMENAME=WOODSTOCK, SOMEOTHERNAME=JIMMY, can I **lowercase** **`WOODSTOCK`** and **`JIMMY`** (to woodstock and jimmy) on the basis they are between `=` and `,`?

It is possible with GNU sed. Choose one of these two forms based on the greediness of the replacement.


sed 's|=.*,|\L&|' file
sed 's|=[^,]*,|\L&|' file


As the manual states, "`\L` turns the replacement to lowercase until a `\U` or `\E` is found". `&` is the text matched by the regex.

* * *

I have modified the sample file to show that you should wisely choose between the geedy `=.*,` and the non-greedy `=[^,]*,` regexes:


$ cat file
SOMENAME=WOODSTOCK,
SOMEOTHERNAME2=JIMMY,WOODSTOCK,FINISH
$ sed 's|=.*,|\L&|' file
SOMENAME=woodstock,
SOMEOTHERNAME2=jimmy,woodstock,FINISH
$ sed 's|=[^,]*,|\L&|' file
SOMENAME=woodstock,
SOMEOTHERNAME2=jimmy,WOODSTOCK,FINISH