If you change the port of SSH, change it to still use a port under 1024. On most Unix systems these are privileged ports that require root to open. This ensures that if there is a process listening there that it was opened by root and not some intruder hoping to get your password to sudo to higher privileges.

Regarding removing reserved space:

Be careful doing this on some file systems. Some filesystems may need to write more data to a journal or are set up with copy-on write and will not be able to delete files if you have no space left on the disk. Reserving a little extra space for this can be necessary. A little extra space also lets you have some space to work with if you need to temporarily create or move files before you can free up the space.

Also, if you're going to use a non-standard port, set up your .ssh/config!

    Host s
        hostname server
        port 666

http://www.commandlinefu.com/commands/browse/sort-by-votes

Being on a Mac, I didn't have the rename or prename command, but after a lot of searching, found it here:

http://www.perlmonks.org/?node_id=303814

Reduce, on the other hand, is a pain; a simple > $$.out or similar on the xargs commandline probably won't work, best to wrap it up in a standalone script that does the same thing to guarantee you've got a new pid.

Then you get something like:

    $ cat batch.sh
    #!/usr/bin/sh
    do_something_expensive $1 > tmp_$$.out
    $ find -print0 | xargs -n 1 -0 -I{} -P 4 bash ./batch.sh {} && cat tmp*out > batch.out && rm -rf tmp*out

    cat somefile | nc -q1 -l -p8081

     nc -q1 -l -p8081 < somefile

  cat [one-file] | less

  less [one-file]

    tail errors.log

    tail errors.log -n 50

The script under "crash test dummy" is hackish and full of race conditions, but that's perhaps acceptable in that case.