shell scripting
 

well i have just started with shell scripting...
i need help regarding a script

how to find all child processes of a parent process given to script as argument.

i would like to know the methodology as well as approach.

thanks in advance

Hello and Welcome to LinuxQuestions,

This sounds like homework to me. LQ users are not in the habit of doing the legwork for you, so you'll have to demonstrate what you already have put together and where it's failing or where errors arise. Then we'll try to help you out.

Kind regards,

Eric

i am no longer in school....
anyways i was trying with ps but it did not help me..
i was trying to do something like this
ps -o user,pid,ppid,command -ax|grep -v root
but didnt work for me

Hello,

OK, I'll take your word for it :)

Did you have a look at the man page of ps?
A quote from that same man page:
If you take the middle one, substitute euid with user and pipe it into grep -v to exclude root like this:
you'll get this as output:
I'll let you figure out what options you want to suppress from the command.

Kind regards,

Eric

basically i have tried these things,grep -v root,but it just shows me the fields,
it has to be a shell script so i just was thinkn whether i should do 2 ps first to get
the ppid and then to get the pid,but i am losing track after this.

i hv just started,so any help would be of great help.

thanks a lot.

If you are just starting shell scripting I highly recommend these:
http://rute.2038bug.com/index.html.gz
http://tldp.org/LDP/Bash-Beginners-G...tml/index.html
http://www.tldp.org/LDP/abs/html/

Hello,

It all bottles down to what you really need, if you only need user, ppid, pid and command for any user except root, then this will do:
That will give you output like this example from my laptop:
Now, you're talking about a script. What exactly do you want to do with it? Do you want to list all child processes of a particular ppid using that script? Or just sort the list of commands depending on their parent process ID? A bit more detail of what you exactly want will help out a lot. Also it would be great if you posted already what you have for your script and not only what command(s) you use or are thinking about.

And do take a look at the links chrism01 pointed you too, they're pretty good when you're starting with Bash scripting.

Kind regards,

Eric

have you tried ps --ppid <parent process id>
 

have you tried ps --ppid <parent process id>. Get the parent process id in your script. Then echo the output of ps --ppid < parent pid>

temp1=$( ps -ef | grep $1 | awk 'NR==1 {print $2}') # this gets the pid of the service
echo $temp1
temp2=$(ps -ef | wc -l) # no of iterations echo $temp2
for(( i = 2 ; i <= $temp2 ; i++ ))
do
temp3=$(ps -ef | awk NR==$i'{ print $3 }') # picking up the ppid of processes
# echo temp3 == $temp3
# echo temp2 == $temp2
if [ $temp1 -eq $temp3 ] ; then
temp4=$(ps -ef | awk NR==$i' {print $8}') # if there is a match cut the field containing name
echo "pid : $temp1"
echo "ppid : $temp3"
echo $temp4
fi
done




this is what i have done..basically a process is given as cmdline argument...and my script tries to find the names of all the children of that process...only prob with this script when i tested with kthreadd as the parent process was it showed 29 of the child processes instead of 41 which it should have shown.

The whole scripting approach to me looks like overkill :}

Wrap that into a function and you're away laughing!



Cheers,
Tink

hail tinker
 

^^^ that was just awesome!!!! its really wonderful to know things and that too when it is so special!!! thanks a lot.kudos.
however ,i would like to know y my script was
showing only 29 of the possible 41 children.