POSIX Update: Shell and Utilities.

[WU SHI-KUEI]

My AT&T Release 5.0 (June 1982) manual page for 'test' reads in part:

WARNING
     In the second form of the command (i.e., the one that uses [], rather
     than the word *test*), the square brackets must be delimited by
     blanks.
     Some UNIX systems do not recognize the second form of the command.