From: Chet Ramey <chet.ramey@case.edu>
To: Adam Thornton <athornton@gmail.com>,
The Eunuchs Hysterical Society <tuhs@tuhs.org>
Subject: Re: [TUHS] Shell builtin exec
Date: Tue, 20 Aug 2019 20:38:08 -0400 [thread overview]
Message-ID: <83aa800b-76e8-7d72-8f1b-2148e36eec05@case.edu> (raw)
In-Reply-To: <CAP2nic1SEFg=e4htyw_23KAL_pUC98JL4XDoWLKwU365BMWXxg@mail.gmail.com>
On 8/20/19 5:10 PM, Adam Thornton wrote:
> This is probably the place to ask:
>
> I understand why the shell builtin "exec" is the same as the syscall exec()
> in the sense of "replace this process with that one." But why is it also
> the way to redirect filehandles in the current shell? (That is, why isn't
> the redirection named something else?)
It was probably a side effect that turned out to be useful. The `exec'
builtin performs redirections without a way to undo them, because why
bother, and executes its arguments as a command with arguments, as if it
were in a child process.
The original Bourne shell just performed the redirections and returned
if there weren't any arguments, leaving the non-undoable redirections
in place.
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU chet@case.edu http://tiswww.cwru.edu/~chet/
prev parent reply other threads:[~2019-08-21 0:39 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-20 21:10 Adam Thornton
2019-08-20 22:00 ` Warren Toomey
2019-08-21 0:38 ` Chet Ramey [this message]
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