Re: How to make 'cd' errors stop a rule?

[David Boyce]

At 10:13 PM 12/4/2005, Dave Hylands wrote:
> HI Tommy,
>
> On 12/4/05, Tommy Nordgren <address@hidden> wrote:
> > Splitting into two lines won't work, since that will change how the
> > command works
>
> Doh.
>
> > if the directory exists.
> > Instead use:
> >         cd bogus-this-is-not-a-real-directory && ls -l
>
> It was on the tip of my tongue to suggest that, but somehow I thought
> it would complicate things - Sigh,

The full story is a little more complicated than this, however. 
Although the OP didn't mention a platform it's presumably Linux, 
because for complex historical reasons[*] the real Bourne shell 
treats cd differently from other commands; it NEVER continues past a 
failed cd whether you use "&&" or ";".  See below, on Solaris:

% /bin/sh -c "false; date"
Sun Dec  4 22:38:21 EST 2005

% /bin/sh -c "cd /fgfgfgfg; date"
/bin/sh: /fgfgfgfg: does not exist

So the situation the OP describes is impossible on a traditional Unix 
system and the provided solution wouldn't help anyway.

I don't have access to a Linux machine at the moment. However, when I 
take the same Makefile and add SHELL=/bin/bash, both problem and 
solution are as described. Bash is supposed to behave in a 
Bourne-compatible manner when invoked as /bin/sh, so as I see it 
either (a) the OP has set SHELL=/bin/bash in the makefile and not 
told us or (b) bash is incompatible with Bourne in this way.

-David Boyce

[*] "Complex historical reasons" means that I read about why the 
shell treats cd specially once but don't remember the details. I 
believe the basic idea was to protect against the sort of carnage 
that can be caused by a typo in "cd /tmp; rm -rf *"