Can somebody tell me how we can write an equivalent of  dup2()
function without using fcntl function?

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In article <60aab6b4.0401192254.6b4132ed@posting.google.com>,
amujoo@yahoo.com (Ash) wrote:
quote:

> Can somebody tell me how we can write an equivalent of  dup2()
> function without using fcntl function?


Close the target FD, then call dup() repeatedly until it returns that
FD.  Then go back and close all the other FDs that were opened in the
loop (so you'll have to keep a list of them as you go).

--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***

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Barry Margolin <barmar@alum.mit.edu> writes:
quote:

> In article <60aab6b4.0401192254.6b4132ed@posting.google.com>,
>  amujoo@yahoo.com (Ash) wrote:
> 
>
> Close the target FD, then call dup() repeatedly until it returns that
> FD.  Then go back and close all the other FDs that were opened in the
> loop (so you'll have to keep a list of them as you go).


That's not exactly equivalent.  dup2() is atomic, i.e. there is no
instant where the target fd is invalid.

--
Måns Rullgård
mru@kth.se

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In article <yw1xwu7now5w.fsf@ford.guide>, mru@kth.se (Måns Rullgård)
wrote:
quote:

> Barry Margolin <barmar@alum.mit.edu> writes:
> 
>
> That's not exactly equivalent.  dup2() is atomic, i.e. there is no
> instant where the target fd is invalid.


OK.  If the process is multi-threaded, it needs to disable thread
switching first.

--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***

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