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$ ps | grep django
28006 ttys004    0:01.12 /usr/bin/python bin/django celeryd --beat
51393 ttys005    0:01.45 /usr/bin/python bin/django celeryd -l INFO
51472 ttys005    0:01.29 /usr/bin/python bin/django celeryd -l INFO
51510 ttys005    0:01.89 /usr/bin/python bin/django celeryd -l INFO
51801 ttys005    0:01.83 /usr/bin/python bin/django celeryd -l INFO
53470 ttys005    0:03.97 /usr/bin/python bin/django celeryd -l INFO
53780 ttys005    0:00.00 grep django

Is there a way to prevent the last process (that is, the grep that was started at the same time as my ps command) being reported?

(I started trying to come up with a regex that would match the literal but not match itself, but that seemed, um, not the right approach...)

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5 Answers

up vote 52 down vote accepted

+1 for @jamzed terse answer, however the OP might need some explanation:

ps | grep "[d]jango"

Using that regex you are launching a process which its ps string will not match itself, since the regexp matches "django" and not "[d]jango". That way you'll exclude the process that has the string "[d]jango" which in this case is grep; The same can be applied to pgrep, egrep, awk, sed, etc... whichever command you used to define the regex.

From man 7 regex

   A bracket expression is a list of characters enclosed in "[]".  It nor‐
   mally matches any single character from the list (but see  below).   If
   the  list  begins  with  '^',  it matches any single character (but see
   below) not from the rest of the list.  If two characters  in  the  list
   are  separated  by '-', this is shorthand for the full range of charac‐
   ters between those two (inclusive) in the collating sequence, for exam‐
   ple,  "[0-9]" in ASCII matches any decimal digit.  It is illegal(!) for
   two ranges to share an endpoint, for example, "a-c-e".  Ranges are very
   collating-sequence-dependent,  and portable programs should avoid rely‐
   ing on them.
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2  
Cool. I'm actually pretty comfortable with regexs but couldn't immediately think of a way to prevent the regexp matching itself. Enclosing a letter in square brackets makes perfect sense. (Including something like [^!] would also work...) –  Steve Bennett Mar 9 '12 at 11:23
1  
That's nice and crafty. –  ash Mar 9 '12 at 21:09
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Oh wait, this works:

ps | grep django | grep -v grep
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6  
Only if the process command line doesn't legitimately include grep, which you cannot count on in the general case. –  Michael Kjörling Mar 9 '12 at 12:41
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Use pgrep instead: pgrep -lf django

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As usual I forgot to mention the platform (OS X in this case). Presumably pgrep works on various linuxes. –  Steve Bennett Mar 9 '12 at 11:30
    
I don't agree, @ramruma . I came to this thread precisely because pgrepgives me exactly this problem. But I must say I am testing it in CygWin (where ps can not show the full command line of the process). –  Sopalajo de Arrierez Apr 4 at 2:28
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ps | grep [d]jango

ps | grep d[j]ango

...

ps | grep djang[o]

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ps -d | grep django

from man ps:

 -d                  Lists information  about  all  processes
                     except session leaders.
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still shows grep on mine... –  Kevin Jun 23 '13 at 21:03
    
Yep, that works for me on OS X. –  Steve Bennett Jan 29 at 5:54
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