use of parallel with command line text files

[Alle Meije Wink]

Dear all

I found GNU Parallel whilst trying to run concurrent jobs on my
quadcore processor (according to my system load viewer on Ubuntu I
have 8 CPUs!).

The things that I try to do are different calls to a program with many
arguments. I thought it would be easiest to run them from a text file
that contains one of those commands on each line.

The page http://lwn.net/Articles/395090 suggests that this is possible
with parallel using 'cat commands.txt | parallel'.

However when I do that with my file it does nothing. No log files, not
even screen output.

Another of my attempts is a 'commands' file made of calls to ls and
writing them to separate files:
printf "/bin/ls > ./ls1.txt\n/bin/ls > ./ls2.txt\n/bin/ls >
./ls3.txt\n" > lstest.txt
. lstest.txt
rm ls?.txt
cat lstest.txt | parallel

Sure enough, the 'normal' call to lstest.txt gives 3 text files with
the directory listing, but again, the call to parallel does nothing
(and gives no log/screen output).

Am I doing something wrong? Is there an easy example to see if
parallel works in this way (the 'cat' way) on my computer?

Thanks very much
Alle Meije Wink