21 Aug
2019
21 Aug
'19
12:38 a.m.
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(a)case.edu http://tiswww.cwru.edu/~chet/