Replacing some characters in a string with another character?

Question

I have a string like <!-- language: lang-none --> AxxBCyyyDEFzzLMN I want to replace all `x` and `y` and `z` with `_` so that the output is A_BC_DEF_LMN How to do that? I know a series of echo "$string" | tr 'x' '_' | tr 'y' '_' will work, but I want to do that in one go, without using pipes. EDIT: The following worked echo "$string" | tr '[xyz]' '_'

Answer 1

You can also use sed with multiple -e flags to accomplish this. If you're reading from a file, the -i flag will work in-place on the file, and you can provide it as an argument after the -e flags.

echo "$string" | sed -e 's/x/_/g' -e 's/y/_/g' -e 's/z/_/g'

Or in-place:

sed -i -e 's/x/_/g' -e 's/y/_/g' -e 's/z/_/g' filename.txt