In sh, is '[' a portable synonym

[Doug Gwyn <gwyn>]

If your Bourne shell has "[" built-in, it will probably have
"test" built-in, too, so the efficiency argument is moot.

I would like to again make the point that NOTHING anyone does is
going to guarantee that ANY particular code (shell script or not)
will necessarily work on all implementations of UNIX.  The approach
I prefer is to provide as close to the same common environment as
possible everywhere; this reduces porting problems substantially.