Directory for shared locks

[Ole Tange]

Currently ~/.parallel/ is used for locks, control paths for -M, and
temporary files for loadavg and swap_activity. This is chosen because
if you run on multiple servers ~/ is likely to be shared amongst them,
where as /tmp is likely to be local to the machine. And you want a
shared lock so that if you run 'sem --id foo' then only one process is
being run no matter how many machines it is being run on.

Apparently some users do not have write access to their home dir(!),
so I am considering having a variable so you can point ~/.parallel to
another place.

$PARALLELDIR or $PARALLEL_DIR seem like reasonable choices for me.
They will of course default to ~/.parallel.

Do you have a better idea for solving the issue or for the variable name?


/Ole