Not that this isn't a good suggestion, but be careful as ps usage and arguments can vary greatly between OSen (and sometimes even between releases of the same OS :). While the example given works fine on Linux, on all three of OS X, FreeBSD, and OpenBSD it'll still print a header line even when given a single pid (the -h means "print headers every page of output" according to the man page, although it doesn't seem to do anything different that I can tell . . .).

I won't even get into SysV-esque ps . . .

Update: Reworded to make more clear that it's the BSD-y ones that insist on a header.