is there a bug in tac when it interpret REGEXP for separator

Hallo,

I want to turn round a datastream with tac, not every line but every
sign.

Now my tests:

wim@g8ser001:~/tmp> echo -e "abbc\ndef" | tac -rs \.

fe
dcbbawim@g8ser001:~/tmp>
this ist wrong.


wim@g8ser001:~/tmp> echo -e "abbc\ndef" | tac -rs \[^.\]

fed
cbbawim@g8ser001:~/tmp>
this is right but I dont understand how tac interpret the REGEXP because
^ in grep is to negate . When tac the ^ to interpret as linestart then
must this also work:

wim@g8ser001:~/tmp> echo -e "abbc\ndef" | tac -rs \[.^\]
abbc
def
wim@g8ser001:~/tmp>
it dont work.

wim@g8ser001:~/tmp> tac --version
tac (textutils) 2.1
Written by Jay Lepreau and David MacKenzie.


greetings

Winfried Münch

mailto: [email protected]