[CentOS] sendmail and rbl blocking - generating statistics
debian at herakles.homelinux.org
Wed Mar 14 22:56:36 UTC 2007
Will McDonald wrote:
> On 14/03/07, John Summerfield <debian at herakles.homelinux.org> wrote:
>> Ryan Simpkins wrote:
>> > Am I using time right to measure it?
>> No, you're timing the cat only.
> I don't think that's the case, you know. If I run the following:
[summer at bilby ~]$ time sleep 10s;sleep 10s
[summer at bilby ~]$ time sleep 10s|sleep 10s
[summer at bilby ~]$ time sleep 10s | time sleep 10s
0.00user 0.00system 0:09.99elapsed 0%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+150minor)pagefaults 0swaps
[summer at bilby ~]$
> [wmcdonald at stella ~]$ ls -lh /tmp/messages.1
> -rw-r--r-- 1 root root 4.3M Mar 14 20:03 /tmp/messages.1
> [wmcdonald at stella ~]$ time cat /tmp/messages.1 1> /dev/null
> real 0m0.018s
> user 0m0.001s
> sys 0m0.017s
> [wmcdonald at stella ~]$ time cat /tmp/messages.1 | grep '*.foo' 1> /dev/null
> real 0m0.047s
> user 0m0.021s
> sys 0m0.026s
> Running both commands repeatedly shows similar time differences, I
> think 'time''s timing the execution time of the whole command.
I think that writing to a pipe is more expensive than writing to
/dev/null. Needs buffering etc.
time cat /tmp/messages.1 | grep \ | grep '*.foo' 1> /dev/null
1aaaaaaa at coco.merseine.nu Z1aaaaaaa at coco.merseine.nu
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