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Re: [minor] "precision" of $SECONDS

From: Chet Ramey
Subject: Re: [minor] "precision" of $SECONDS
Date: Thu, 25 Feb 2016 10:48:51 -0500
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On 2/25/16 8:18 AM, Stephane Chazelas wrote:

> Similar features would be welcome in bash.
> bash has "times" that gives you CPU time with sub-second
> granularity. It's got a "printf %T" a la ksh93, but no %N, its
> $SECOND is only integer (and currently has that issue discussed
> here).

Because bash doesn't have floating point arithmetic.  There's no
real reason to have $SECONDS in a format you can't use to perform

Bash's %T implementation doesn't have %N because it uses the libc
strftime(3), and as far as I know, no strftime provides it.  I assume
that ksh93 implements it internally as part of libast.

Bash doesn't have a `sleep' builtin at all, but there is a loadable
sleep builtin that offers sub-second granularity.

``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU    address@hidden    http://cnswww.cns.cwru.edu/~chet/

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