Re: variables set on command line

[Eric Blake]

On 08/24/2011 09:24 AM, Sam Steingold wrote:
> CYGWIN_NT-5.2-WOW64 sds 1.7.9(0.237/5/3) 2011-03-29 10:10 i686 Cygwin
> BASH_VERSION='4.1.10(4)-release'
>
> at the bash prompt I observe this:
> $ f(){ echo a=$a b=$b c=$c ; }
> $ unset a b c
> $ a=a b=b f
> a=a b=b c=
> $ f
> a= b= c=
> which I believe is correct (i.e., variables set in "a=a b=b f" are unset
> after f terminates).

This is bash's default behavior, but it violates POSIX.

> alas, when I call /bin/sh on the same machine, I see this:

That tells bash to strictly obey POSIX, so you get the POSIX behavior.

> f(){ echo a=$a b=$b c=$c ; }
> f
> a= b= c=
> a=a b=b f
> a=a b=b c=
> f
> a=a b=b c=

Which is indeed correct under the rules for POSIX (basically, POSIX 
requires function calls to behave like special built-ins, such that 
changes to the environment persist after the function call - the bash 
developer thinks the posix rule is counterintuitive, which is why the 
default bash behavior is opposite the posix behavior).

Your question is not cygwin-specific.

> is this the expected behavior?

Yes.

--
Eric Blake   eblake@redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org