cksfv prints output, but it cannot be 'caught'

[Daan]

Hi.

The last command in the bash code below gives output I did not expect.

daan@schmauck:~/tst$ ls
abc  abc.sfv  abx.sfv  sfvsort
daan@schmauck:~/tst$ ls | tail -n1
sfvsort
daan@schmauck:~/tst$ cksfv -f abc.sfv
--( Verifying: abc.sfv )--------------------------------------------------------
abc                                               OK
--------------------------------------------------------------------------------
Everything OK
daan@schmauck:~/tst$ cksfv -f abc.sfv | tail -n1
--( Verifying: abc.sfv )--------------------------------------------------------
abc                                               OK
--------------------------------------------------------------------------------
Everything OK
daan@schmauck:~/tst$

I expected there the out put to be

Everything OK

, just like the output of the second command is only one line. I've also tried saving the output of the last command to a variable:

daan@schmauck:~/tst$ result=$(cksfv -f abc.sfv | tail -n1)
--( Verifying: abc.sfv )--------------------------------------------------------
abc                                               OK
--------------------------------------------------------------------------------
Everything OK
daan@schmauck:~/tst$ echo $result

daan@schmauck:~/tst$

The variable is empty! What is going on here?

[Franklin52]

It seems that your command outputs his messages to stderr.
Redirects stderr to stdout and see what happens:

2>&1 cksfv -f abc.sfv | tail -n1

Regards

[Daan]

daan@schmauck:~/tst$ 2>&1 cksfv -f abc.sfv | tail -n1
Everything OK

Thanks.

Can you explain what it does?

[Franklin52]

To understand how it works you can have a read of section 8.2.3 of this document:

http://tldp.org/LDP/Bash-Beginners-G...ers-Guide.html

Regards