[TUHS] Shell control through external commands

Dave Horsfall dave at horsfall.org
Fri Jul 15 11:04:45 AEST 2016

On Thu, 14 Jul 2016, shawn wilson wrote:

> I've always been curious though - what was the reason behind 
> implementing /bin/[ ? IDK any shell where this isn't implemented - I 
> always assumed it's a POSIX compatibility stopgap older systems needed 
> to stay compliant with their shipped shell.

To implement:

    [ blah ]

when it wasn't a built-in (there were few built-ins in those days).

I have no idea why it's still there...  A Posix requirement, along with 
really unsafe functions?

By the way, on both Mac and FreeBSD (I can't be bothered checking my
Penguin box) "true" and "false" are binaries (and aren't even linked).

Dave Horsfall DTM (VK2KFU)  "Those who don't understand security will suffer."

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