test the exit status inside a shell

[David Elliott]

In article <826 at philmds.UUCP> leo at philmds.UUCP (Leo de Wit) writes:
>while command1; do commands; done  # while command1 succeeds do the commands
>until command1; do commands; done  # until command1 succeeds do the commands
>if command1; do commands; done     # if command1 succeeds do the commands
	      ^^           ^^^^

"if" in sh uses "then" and "fi", not "do" and "done", but that's not what
I followed up for.

An interesting note about while and until is that the actual syntax is

	while list; do list; done

where a "list" is a list of commands (the semicolons can be newlines).

This means that the loop

	a=no
	while
		echo "Enter a new value for a: \c"
		[ "$a" != "no" ]
	do
		read a
		echo "Entered $a"
	done

is a legal loop.  I've only seen this used once, but it could be useful
as fast machines make it more reasonable to use sh to write interactive
commands.

-- 
David Elliott		dce at mips.com  or  {ames,prls,pyramid,decwrl}!mips!dce