As I understand it, xargs only runs on the local machine; GNU parallel can run on remote machines as well. So parallel is the cluster-friendly version of xargs's -P.

Yep. There also is dxargs which looks very useful http://www.semicomplete.com/blog/geekery/distributed-xargs.h...

Please read http://www.gnu.org/software/parallel/man.html#differences_be... before selecting dxargs.

Please read http://www.gnu.org/software/parallel/man.html#differences_be... before selecting xargs.

Don't you need

    echo "file1 file2" | xargs -P2 -n1 gzip

?

Probably, although it doesn't seem to be the focus of xargs.

And the version of xargs that is included with Solaris 10 doesn't have the -P option. In which case, installing gnu parallel is a slightly easier option than installing a different version of xargs.