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From: Norman Wilson <norman@oclsc.org>
To: tuhs@tuhs.org
Date: Tue, 29 Sep 2020 15:15:06 -0400
Message-ID: <1601406910.6529.for-standards-violators@oclsc.org>
Subject: [TUHS] SH script formatting
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if test; then
	stuff

and

if test
then
	stuff

are functionally equivalent.  I wouldn't say one or the
other `is preferred.'  I use the former because I think
it's a little more readable because more compact.  But
it's really a matter of style, like whether you write

	if (test) {
		(multi-statement block)

or

	if (test)
	{
		(multi-statement block)

I have a stronger opinion about those who use overly-
cryptic constructions like

	test && {
		shell commands
	}

because it means exactly the same thing as

	if test; then
		shell commands

but is more obscure to read.  But again it's a question
of style, not of dogma.

As an aside, I think one excuse that is sometimes used
for that sort of construct is when it's

	test || {
		commands
	}

because Bourne's original shell had no not operator.
For a long time after shell functions appeared, I would
add this function to any of my shell scripts that needed
it:

	not() {
		if "$@"; then
			return 1
		else
			return 0
	}

so I could say

	if not test; then
		commands
	fi

Modern Bourne-shell descendants have a built-in ! operator:

	if ! test; then
		commands
	fi

I'm not keen on most of what has been stuffed into bash and
ksh and the like, but ! is a real improvement.  I believe
POSIX mandates it, and I think they're right.

Norman Wilson
Toronto ON