Question

I run the following code

sed 's/\([^ ]+\) your \([^ ]+\)/ \2\1er/' < fail

The file fail is

fail your test

The above command gives me

fail your test

although it should give “testfailer”.

The second and first globs \2\1 should be at the start of the word “er”.
This suggests me that the problem may be in the regexes in the search part.
However, they seem to be correct for me.

Do you see any mistake in the code?

Answer 1

Your code does work when you escape the plus signs:

sed 's/\([^ ]\+\) your \([^ ]\+\)/\2\1er/' < fail