nested if's in csh

[moss%brl-vld at sri-unix.UUCP]

From:      Gary S Moss ~Software Development Team~ <moss at brl-vld>

> The following shell script, when run with the four permutations of inputs
> t 0 0
> t 1 0
> t 0 1
> t 1 1
> works correctly in all cases.
>
> #! /bin/csh -f
> set a = $1
> set b = $2
> if ( $a ) then
>    if ( $b ) then
>	echo a and b
>    else
>	echo a and not b
>    endif
> else
>    if ( $b ) then
> 	echo not a, but b
>    else
> 	echo neither a nor b
>    endif
> endif
>
> However, if spaces are left out between the "if" and the "(", it no
> longer works correctly. Thus the space appears to be the key. This seems
> to be a bug.

This is not the same situation as Jim presented.   Jim's problem stems
from having a nested 'if' in the 'else' branch of the outside conditional
such that an 'else' is followed immediately by the nested 'if'.
Your example has such a situation :

	else
	    if ( $b ) then ...
	
HOWEVER, even though the bug in the csh syntax makes this ambiguous,
the two possible expressions are functionally equivalent, the alternate
is below.