On 2007-08-21 17:50:53 -0600, Bob Proulx wrote: > Vincent Lefevre wrote: > > vin:~> bash > > [EMAIL PROTECTED]:~$ touch exists > > [EMAIL PROTECTED]:~$ [ ! -a exists ] || echo found > > [EMAIL PROTECTED]:~$ /usr/bin/[ ! -a exists ] || echo found > > found > > You are running afoul of -a ambiguity. Stop that. Do you mean AND > such as -a intends?
I didn't mean any specific behavior. I just noted that /usr/bin/[ and [ bash builtin are not compatible. > Use -e if you want to test for simple file existence. Of course, but I also have to live with scripts (not written by me) that use '-a' (and of course, I cannot really in advance if '-a' is used or not). That's the real world. :( Now, what about the following test, which does not test file existence? [EMAIL PROTECTED]:~$ [ true -a \( ! -a \) ] && echo OK bash: [: `)' expected, found ] [EMAIL PROTECTED]:~$ /usr/bin/[ true -a \( ! -a \) ] && echo OK [EMAIL PROTECTED]:~$ This is unspecified by POSIX, but test(1) has its own documentation. If you prefer, the bash builtin breaks the compatibility with test(1) even if it is non-standard. > > Are you sure that > > > > [ "$foo" = "" ] > > > > isn't POSIX sh? IMHO, it is perfectly valid (note: the quotes are > > important). > > POSIX defines this okay but as I was noting the traditional use was to > use the X to prevent the old test from parsing it as an option. In > the traditional environment this was not protected by the new POSIX > requirement to count the number of program arguments provided. OK, I now understand. I read somewhere else that the cause was empty strings. Even in a POSIX environment, there's still a problem if $foo is '!' (if I'm not mistaken, this is an "unspecified results" case). > I still prefer to use -z and -n instead. Yes. -- Vincent Lefèvre <[EMAIL PROTECTED]> - Web: <http://www.vinc17.org/> 100% accessible validated (X)HTML - Blog: <http://www.vinc17.org/blog/> Work: CR INRIA - computer arithmetic / Arenaire project (LIP, ENS-Lyon) -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
