On Jan 26, 2011, at 11:22 AM, AJ ONeal wrote:
> I don't know about y'all, but I often find cases where I wish I had msleep in
> bash.
Just curious... what are some cases where you need this functionality?
Precision timing would be hard to do in a shell script due to the startup
overhead of your program, but I can see times when pauses on the order of a
half- or quarter-second could be useful.
Interestingly enough, sleep(1) on my Mac says it accepts a fractional value
(i.e. sleep 0.5). The man page on my Ubuntu system doesn't mention this, but
it still seems to work:
linux_bash$ date +%s.%N; sleep 0.5; date +%s.%N
1296067377.322561535
1296067377.825704857
Sadly, the date command on the Mac doesn't understand %N, so I have to fake it
with perl:
darwin_bash$ alias hrtime="perl -e 'use Time::HiRes qw(time); print time,
\"\n\";'"
darwin_bash$ hrtime; sleep 0.5; hrtime
1296068112.03389
1296068112.55211
Looks like the overhead is acceptable for sleeps longer than 1/100 of a second
or so, on modern hardware, at least.
-jan-
--
Jan L. Peterson
http://www.peterson-tech.com/~jlp/
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