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Old 10-22-2010, 03:38 PM   #1
jasonws
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Grep for the result of a command within the result of another command


Hey, I'm trying to figure out how to merge these two commands. The first one needs to be plugged into the second where it says <TTY>. I'm sure it's pretty simple, but I haven't yet found a way to do it. Thanks! -Jason

#Finds the current session of the given user <user>
<TTY> = w |grep <user> |grep 0.00s | cut -c 10-15

#Returns all the pids for all but the current session <TTY> of the given user <user>
ps uU <user> |grep pts/ |grep -v <TTY> | cut -c 10-14
 
Old 10-22-2010, 04:00 PM   #2
MensaWater
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Code:
ps uU <user> |grep pts/ |grep -v $(w |grep <user> |grep 0.00s | cut -c 10-15) | cut -c 10-14
 
Old 10-22-2010, 04:11 PM   #3
jasonws
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Sorta figured this out, not really. Help?

Hey, I used the for expression to handle this problem, but apparently this command isn't formed correctly and I get > as a result.

$for tty in 'w |grep dsi |grep 0.00s | cut -c 10-15'; do for pid in 'ps uU dsi |grep pts/ |grep -v $tty | cut -c 10-14'; do kill $pid; done
>

To test it, I tried this command, with the following result:

$for tty in 'w |grep dsi |grep 0.00s | cut -c 10-15'; do echo $tty; done
w |grep dsi |grep 0.00s | cut -c 10-15

Not sure what I'm doing wrong. I would think I'd get some pids, since that's what I get when I run the following command:

w |grep dsi |grep 0.00s | cut -c 10-15

Any ideas?

Thanks,
Jason
 
Old 10-23-2010, 01:22 AM   #4
grail
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Quote:
input -> for tty in 'w |grep dsi |grep 0.00s | cut -c 10-15'; do echo $tty; done
output -> w |grep dsi |grep 0.00s | cut -c 10-15
So what is this telling you?

It is saying that tty only gets one value, that being the string 'w |grep dsi |grep 0.00s | cut -c 10-15', which it is then echoing.
Seems to have performed its task correctly.

I am guessing your question is why did it not return the values from your commands?
Answer: You have input a string and not a command substitution.

Have a look at MensaWater's solution and your answer lay there on how to correct it.
 
Old 10-25-2010, 08:27 AM   #5
jasonws
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Thanks, MensaWater and grail. I should have reloaded the page before posting last Friday... Here's the final command that kills the PIDs:

ps uU <user> |grep pts/ |grep -v $(w |grep <user> |grep 0.00s | cut -c 10-15) | cut -c 10-14 | xargs kill
 
Old 10-25-2010, 09:07 AM   #6
grail
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You should probably be a little cautious ... what happens when your username exceeds 10 characters? Your first cut will be in a bit of strife
 
Old 11-18-2010, 02:39 PM   #7
jasonws
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In my case the usernames will always be 3 characters. Nothing to worry about. Thanks!
 
  


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