Backtick versus $()

Thorsten Glaser tg at
Thu Feb 24 20:51:46 UTC 2011

Andres Perera <andres.p <at>> writes:

> "mandated by posix" and reality usually aren't in sync, as i'm sure you know 

In this case, closely enough.

> now since you pointed out solaris

It’s just /bin/sh on long outdated versions (newer ones, both
from Horracle and not, have AT&T ksh93 there instead). No need
to use it, anyway. sh scripts can usually depend on a POSIX
shell (and it’s sensible to do so). Some operating environments
have guaranteed that (MirBSD even guarantees mksh but Debian
Policy §10.4 explicitly states POSIX plus a few extensions).

And AFAIK all FreeBSD® shells have it.

“It is inappropriate to require that a time represented as
 seconds since the Epoch precisely represent the number of
 seconds between the referenced time and the Epoch.”
        -- IEEE Std 1003.1b-1993 (POSIX) Section B.2.2.2

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