On 6/10/20 7:48 AM, Terence O'Gorman wrote:
> Bash Version: 5.0
> Patch Level: 11
> Release Status: release
>
>
> Description:
>
> The 'while read' loop exhibits very different performance depending on
> whether input is via redirection or pipeline (and increasingly diverging
> performance with any increased data). Here are some results from my
> machine (also observed in versions 3.0 and 4.0):
Two forks and one exec are expensive, as are the single-byte reads through
the pipe. The single-byte reads are required because the shell is not
allowed to read ahead in this case, since the remaining input may be
intended for another process.
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU [email protected] http://tiswww.cwru.edu/~chet/
