[ubuntu-florida] Avoid That grep Command in grep Output

[Matt Miller]

This is how I would go about it:

$ pgrep bash | xargs ps -fp
UID        PID  PPID  C STIME TTY      STAT   TIME CMD
millermx  3104  3099  0 08:48 pts/0    Ss+    0:00 /bin/bash
millermx 13662 13659  0 09:58 pts/1    Ss     0:00 /bin/bash
millermx 16247 13659  0 10:36 pts/2    Ss     0:00 /bin/bash
millermx 16405 13659  1 10:46 pts/3    Ss     0:00 /bin/bash


On Wed, Sep 15, 2010 at 10:37 AM, Miano, Steven M.
<Steven.Miano at mybrighthouse.com> wrote:
>
> I've always just done:
>
> $ps aux | grep bash | grep -v grep
>
> Is there something wrong with that?
>
> On the error in the book that's interesting, I wasn't able to reproduce the same error using the same command successively....8.04/LTS/i386
>
> ~Steven
>
> ________________________________________
> From: ubuntu-us-fl-bounces at lists.ubuntu.com [ubuntu-us-fl-bounces at lists.ubuntu.com] On Behalf Of j.e.aneiros [jesus.aneiros at gmail.com]
> Sent: Wednesday, September 15, 2010 9:39 AM
> To: Mailing list for Ubuntu Florida LoCo Team
> Subject: [ubuntu-florida] Avoid That grep Command in grep Output
>
> Hello everyone,
>
> I'm planning to send everyday at least a message to the list with something interesting about Linux. This is the first one.
>
> One week ago I bought the book "Official Ubuntu Server Book, The (2nd Edition)". Being a command line fan I went directly to the section "Cool tips and tricks". I started reading and I found out that the explanation of the first trick is in a certain way wrong.
>
> The idea behind the trick is to avoid the appearance of grep in resulting list for a command like:
>
> janeiros at harlie:~$ ps ax | grep bash
> 13235 tty1     S      0:00 -bash
> 13256 tty1     S+     0:00 /bin/bash /usr/bin/startx
> 16911 pts/0    Ss+    0:00 -bash
> 17005 pts/1    Ss     0:00 -bash
> 17152 pts/1    S+     0:00 grep --color=auto bash
>
> The authors suggest a "trick" running the command in this form:
>
> janeiros at harlie:~$ ps ax | grep [b]ash
>
>  How come when I try the trick is OK the first time and wrong at the second one?
>
> janeiros at harlie:~$ ps ax | grep [b]ash
> 13235 tty1     S      0:00 -bash
> 13256 tty1     S+     0:00 /bin/bash /usr/bin/startx
> 16911 pts/0    Ss+    0:00 -bash
> 17005 pts/1    Ss     0:00 -bash
>
> You can see grep is gone.
>
> And now is back:
>
> janeiros at harlie:~$ ps ax | grep [b]ash
> 13235 tty1     S      0:00 -bash
> 13256 tty1     S+     0:00 /bin/bash /usr/bin/startx
> 16911 pts/0    Ss+    0:00 -bash
> 17005 pts/1    Ss     0:00 -bash
> 17185 pts/1    S+     0:00 grep --color=auto bash
>
> Of course, I did something in between that provoked the change! What was it? Let see if somebody find out what was. The authors' explanation for the trick is not exact!
>
> The explanation is right there at the command line!
>
> If nobody finds out I'll tell you later today.
>
> By the way there is an alternative to the trick but it's longer.
>
> Have a good day!
>
> PS. The outputs of the commands weren't edited at all.
>
> --
> J. E. Aneiros
> GNU/Linux User #190716 en http://counter.li.org
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