question-- Bourne (and C) SHELL

[Daniel R. Levy]

In article <150 at humming.UUCP>, arturo at humming.UUCP (Arturo Perez) writes:
>In the csh you can do something like
>
>ls foo
>if (! $status) then
>   echo "foo exists"
>endif
>
>The  key  thing  here  is  the  ability  to NOT the value of status. How is
>this similar thing done in Bourne shell.
>
>if ! ls foo
>then
>	echo foo does not exist
>fi

To follow your example literally:

ls foo
if test $? -ne 0	# or, "if [ $? -ne 0 ]" is supported by modern /bin/sh's
then
	echo foo does not exist
fi

Of course, there are other ways to check for nonexistence of foo, e.g.:

if [ ! -f foo -a ! -d foo -a ! -p foo -a ! -c foo -a ! -b foo ]

# foo is not a file, a directory, a pipe, a character special device, or a
# block special device

which though "wordier" does not require the spawning of another process
presuming that "test" is a builtin in your shell.
-- 
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