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From: latham@ablnc.ATT.COM (Ken Latham)
Newsgroups: comp.unix.wizards
Subject: Re: /bin/test and stat(2)
Message-ID: <336@ablnc.ATT.COM>
Date: Wed, 7-Oct-87 12:36:35 EDT
Article-I.D.: ablnc.336
Posted: Wed Oct  7 12:36:35 1987
Date-Received: Sat, 10-Oct-87 17:46:33 EDT
References: <9479@brl-adm.ARPA> <29056@sun.uucp> <467@ambush.UUCP> <743@quacky.UUCP>
Organization: AT&T, Maitland, Florida
Lines: 25
Summary: a more direct method

> > >Don't rely on *this* behavior either, check that a string isn't null before
> > >handing it to "/bin/test"!
> >
> >Just how ? Write a specialized c-program "isnull"....er!
> 
> You can use the -a (boolean "and" operator) or -o ("or"). That is
> 
> 	test " $name" != " " -a -d "$name"
> 

The most direct ( and simplest complete ) method I know of is :


	test -n "${name}" -a -d "${name}"

	-n   ---   test if a string is NOT zero length.
	-z   ---   test if a string IS zero length.

Don't let the {}'s get to you, they just delineate the variable name.



					Ken Latham
					AT&T Support
					..!ihnp4!ablnc!latham