How do I ask "if NOT" in shell?

[Maarten Litmaath]

kirkaas at oahu.cs.ucla.edu (paul kirkaas) writes:
\How can one say "if not" in a shellscript; that is, execute the body of
\the "then" only if the argument of "if" returns a non-zero exit status?

Unfortunately there doesn't seem to be a clean way to do this.
The obvious work-around:

	if command
	then
		:
	else
		command
	fi

A cleaner approach:

	if not command
	then
		command
	fi

...where `not' is defined as the following shell function/script:

	${1+"$@"}
	test $? != 0

SunOS 4.0.3c /bin/sh doesn't like a function to be named `!', a shell
script would be OK though.
-- 
A symbolic link is a POINTER to a file, | Maarten Litmaath @ VU Amsterdam:
 a hard link is the file system's GOTO. | maart at cs.vu.nl, mcsun!botter!maart