Question

Can someone explain why this code doesn’t work as expected?
I would expect it only to match the first character, and it does with literal characters, but the wildcard (.) and characters classes behave strangely:

I use -o just to demonstrate exactly how things are matching, it doesn’t change what matches at all.

$ echo foo | grep -o '^.'
f
o
o

Some more unexpected behavior:

$ echo foobarbazquux | grep -o '^[foarqux]'
f
o
o

$ echo foobarbazquux | grep -o '^.[^u]'
fo
ob
ar
ba
zq

Esentially the beginning-of-line matcher (^) is not behaving as expected in these cases. Is there any way to make it behave more normally?

Answer 1

Found it:

Bug

Changelog of fix

Apparently fixed in 2.5.2. Found it via launchpad.