On Sunday 04 July 2010 17:11:11 Christoph Anton Mitterer wrote: > I may have found a place where dash violates POSIX. > > If I do the following: > $ sh > $ set -e > $ false > > it exits, as expected, and specified here > http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#set > > > However, when doing the following: > $ sh > $ set -e > $ . someNonExistentFile > .: 2: foo: not found > $ > > it does not exit.
I don't see any bug here, let me explain: > Now the above documentation for -e says: > When this option is on, if a simple command fails for any of the reasons > listed in Consequences of Shell Errors or *returns an exit status value >0*, > and is not part of the compound list following a while, until, or if > keyword, and is not a part of an AND or OR list, and is not a pipeline > preceded by the ! reserved word, then the shell shall immediately exit. > > "." is described here > (http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#d > ot) where it says all the following: > - If no readable file is found, a *non-interactive shell shall abort*; an > *interactive shell shall write a diagnostic message to standard error*, but > this condition shall not be considered a syntax error. > -EXIT STATUS: Returns the value of the last command executed, or a zero > exit status if no command is executed. dash's manual page says: > If no args are present and if the standard input of the shell is connected > to a terminal (or if the -i flag is set), and the -c option is not present, > the shell is considered an interactive shell. So, in your example what you are running is _an interactive shell_. I would say that's the reason why dash doesn't abort: it is an interactive shell and since 'dot' didn't execute any command it returns a status code of 0. $ dash -c 'set -e; . /dev/foo; echo Exited with status: $?' .: 1: Can't open /dev/foo $ Further confirmation: http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html#tag_02_08_01 HOWEVER, there's something interesting: $ dash $ PS1='dash$ ' dash$ . foo .: 2: foo: not found dash$ . /dev/foo .: 3: Can't open /dev/foo $ It exits even if it is an interactive shell. The only difference between the two is that '. foo' means "look for 'foo' in $PATH and execute its commands," while '. /dev/foo' means "execute /dev/foo's commands." That IMO would be the bug. (FTR, bash and others consider the former form as a combination of the two forms, i.e. they look for the argument in $PATH and if not found they look for it in ./) The problem I see with that interpretation of POSIX, is that there's no way for a script to know if 'dot' failed because the file argument was not readable, even with set -e. Btw, those links point to POSIX:2008, but Debian Policy requires SUSv3 (a.k.a. POSIX:2004.) Cheers, -- Raphael Geissert - Debian Developer www.debian.org - get.debian.net -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected]
