From:	"Mark E." <snowball3 AT bigfoot DOT com>
To:	djgpp-workers AT delorie DOT com
Date:	Thu, 22 Mar 2001 13:19:09 -0500
MIME-Version:	1.0
Subject:	Re: pipe() emulation
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> How is this supposed to be used?  Could you give an example of a
> real-life usage in Bash?

pipe() is used by the command substitution and pipeline portions of Bash. In 
the case of command substituion, Bash essentially does this:
pipe(fildes)
dup2(fildes[1], 1) /* write end of pipe now stdout */
/* perform command */
/* read command output from read end of pipe */

Pipelines such as 'a | b' are more complicated:
pipe(fildes1)
dup2(fildes1[1], 1) /* Write end of pipe 1 is now stdout */
/* run 'a' */
dup2(fildes1[0], 0) /* Read in of pipe 1 is now stdin */
close(fildes1[1]) /* Done with write end of pipe 1*/
/* run 'b' */
close(fildes1[0]) /* Done with read end of pipe 1 */

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