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# 1  
Error Question about awk

Hi,

I am printing the children of a process using this command:

Code:
ps -aef | grep 13783 | grep -v grep | grep -v ps | grep -v $0

and it shows the children correctly. (2 in my case)

The thing is that when I pipe it to awk to get the PIDs like this:

Code:
ps -aef | grep 13783 | grep -v grep | grep -v ps | grep -v $0 | awk '{print $2}'

I get 3 numbers. I don't know where that 3rd number is coming from.
# 2  
I hope not to interfere with your awk learning process, but a look at the ps manpage revealed an easier method to get child processes:

Code:
ps --ppid 13783

# 3  
Thanks. I knew about that, but I need to use awk. Used --ppid before and that one also produces 3 where it should be 2.
# 4  
I can't really tell where it's coming from either, as I can't see your input, and without that, can't follow your logic.

It'd be much easier to control it though, if you weren't running awk | sed | cut | fold | kitchen | sink, just running one awk instead. One process to exclude instead of 9.

Post your input, and post the output you want, please.
# 5  
Quote:
Originally Posted by Corona688
I can't really tell where it's coming from either, as I can't see your input, and without that, can't follow your logic.

It'd be much easier to control it though, if you weren't running awk | sed | cut | fold | kitchen | sink, just running one awk instead. One process to exclude instead of 9.

Post your input, and post the output you want, please.
Ok I solved the issue with the extra number. I had to grep out bash.

Now storing in the array doesn't work

Code:
for child in `ps -aef | grep $pid | grep -v grep | grep -v ps | grep -v $0 | grep -v awk | grep -v bash | awk '{print $2}'`; do
       arrayOfChildren+=("$child")
done

echoing the contents with ps shows:

Code:
PID TTY TIME CMD 5 ? 00:00:00 stopper/0
PID TTY TIME CMD 5 ? 00:00:00 stopper/0

so basically the contents of the array are:
5
5

but before putting into the array I echo the output of
ps -aef | grep $pid | grep -v grep | grep -v ps | grep -v $0 | grep -v awk | grep -v bash | awk '{print $2}'

and i get the correct children PIDs.
# 6  
Quote:
Originally Posted by Corona688
It'd be much easier to control it though, if you weren't running awk | sed | cut | fold | kitchen | sink, just running one awk instead. One process to exclude instead of 9.
It really would.

Quote:
Post your input, and post the output you want, please.
I've seen the output you want, but not the input. So I will take a wild uninformed guess at what you actually want and hope that ps -aef looks the same on my system as yours:

Code:
# Apache's PID is 10820
$ ps 10820
  PID TTY      STAT   TIME COMMAND
10820 ?        Ss     0:28 /usr/sbin/apache2 -D INFO -D SSL -D LANGUAGE -D PHP5
# So, list all PIDs where PPID, col 3, are 10820
$ ps -aef | awk -v PARENT="10820" '$3 == PARENT { print $2 }'

19832
20286
20304
20305
25669
25690
25692
25693
25694
25770
30264

# This time, put them in an array
$ ARRAY=( `ps -aef | awk -v PARENT="10820" '$3 == PARENT { print $2 }'` )

$ echo ${ARRAY[0]}
19832
$ echo ${ARRAY[1]}
20286
$

By hunting for meaningful values rather than blind text matches, all the grep -v | grep -v | grep -v | grep -v | grep -v | grep -v | grep -v | grep -v can be avoided.
# 7  
How about
Code:
ps -aef | awk '$3 == 13783 {print $2}'

? Adapt if PPID is NOT field 3...



EDIT: Hoppla - this is pretty close to what Corona668 posted just a few minutes ago - sorry!

Last edited by RudiC; 11-25-2016 at 04:42 PM..

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