Re: [gentoo-user] "/usr/bin/[" and coreutils

[Michael Mol]

On Thu, Oct 13, 2011 at 9:50 AM, Alan McKinnon <alan.mckinnon@×××××.com> wrote:
> On Thu, 13 Oct 2011 15:38:08 +0200
> Jesús J. Guerrero Botella <jesus.guerrero.botella@×××××.com> wrote:
>
>> Yes, it's a different binary, and it's perfectly usual to find it in a
>> Linux system.
>>
>> But note that, at least in bash, you rarely will be using /usr/bin/[
>> unless you reference it using the full path (either in a relative or
>> absolute way). This is because bash has a builtin that takes over that
>> binary file. You can check that (or any other command) by using the
>> "type" instruction (again, this is for bash).
>>
>> # LC_ALL=C type [
>> [ is a shell builtin
>>
>> The same goes for 'test'.
>>
>> Those binaries are probably there just in case that some init or
>> system script written for a standard bourne shell (like the busybox
>> one) needs it. But don't take my word for it. I am not sure right now.
>
> You might not be sure, but that doesn't stop you still being correct :-)
>
> The binaries are usually POSIX-compliant, whereas the builtins may
> include extra bashisms (which tend to break apps expecting just
> the basic POSIX behaviour)

I haven't encountered POSIX-dependent apps breaking on bash, but I
have encountered the reverse. My most annoying experience was when I
tried building cinelerra on Debian a few years back. Cinelerra's
script started with #!/bin/sh, but depended on bashisms--and I was
running dash.

-- 
:wq