Question

The sed below will output the input exactly. What I’d like to do is replace all occurrences of _ with – in the first matching group (\1), but not in the second. Is this possible?

echo 'abc_foo_bar=one_two_three' | sed 's/\([^=]*\)\(=.*\)/\1\2/'
abc_foo_bar=one_two_three

So, the output I’m hoping for is:

abc-foo-bar=one_two_three

I’d prefer not to resort to awk since I’m doing a string of other sed commands too, but I’ll resort to that if I have to.

Edit: Minor fix to RE

Answer 1

You can do this in sed using the hold space:

$ echo 'abc_foo_bar=one_two_three' | sed 'h; s/[^=]*//; x; s/=.*//; s/_/-/g; G; s/\n//g'
abc-foo-bar=one_two_three