scripting help

Tom Dunne

We have a large number of users connecting to our Red Hat Server via Remote Desktop (long story, don't ask).

What is happening is that they are not logging out of RDP properly, they are simply closing the RD software on their client PC, leaving the XRDP sessions still running. As you can imagine, over time, these build up and prevent further users from connecting.

As such, I want to run a nightly cron job that will kill the xrdp processes. So far, I have the following which gives me the list of PIDS:

ps -ef pid | awk '$1 == "xrdp" { print $2 }'


However, given this list of pids, I am having trouble piping it into the kill command:

ps -ef pid | awk '$1 == "xrdp" { print $2 }' | kill
ps -ef pid | awk '$1 == "xrdp" { print $2 }' > kill
ps -ef pid | awk '$1 == "xrdp" { print $2 }' > kill_list.txt
kill < kill_list.txt

My scripting skills are quite rusty at this stage, so can anyone give me some direction on how to pipe this list into the kill command?

syklops

Could you not just do killall xrdp?

syklops

by the way, what you are looking for is:

for i in `cat kill-list.txt`;do kill $i;done

Khannie

pkill xrdp (as root) should also work (once you're not connected by rdp of course ).

edit: I'm not sure that for loop will work with newline delimiters. I think you need a while loop with a readline:

while read PID; do
kill $PID
done < kill-list.txt

Khannie

One last thing: The reason this isn't working:

ps -ef pid | awk '$1 == "xrdp" { print $2 }' > kill_list.txt
kill < kill_list.txt

Is that you're trying to pass it in through stdin so they're not command line arguments (as kill is expecting). You would probably get away with something like this:

kill $(ps -ef pid | awk '$1 == "xrdp" { print $2 }')

syklops

Khannie wrote: »

pkill xrdp (as root) should also work (once you're not connected by rdp of course ).

edit: I'm not sure that for loop will work with newline delimiters. I think you need a while loop with a readline:

Why would it not work?

Khannie

I remember having issues with for loops and newlines before which made me move to the while loop (with read). The for loop is my favourite instrument of looping in bash by quite a margin, so for me to move to while for newline-y stuff there must have been some reason. I am too lazy to test it though.

syklops

Khannie wrote: »

I remember having issues with for loops and newlines before which made me move to the while loop (with read). The for loop is my favourite instrument of looping in bash by quite a margin, so for me to move to while for newline-y stuff there must have been some reason. I am too lazy to test it though.

Cat blah

ghgh
ghghg
gjgjg
djdjd
eyrytyp

for i in `cat blah`; do echo $i; done

Result:
ghgh
ghghg
gjgjg
djdjd
eyrytyp

Not alot of testing involved. Hence my question.

Khannie

Hmmm. Yeah I just tested it with kill and 2 pid's in a file separated by a newline and it worked perfectly. There was definitely some reason in the past that I used the while loop though (i.e. a for loop had failed). I wasn't familiar with the while read <VAR> syntax, so it required a googling and that's why I remember it. At some point many moons from now when it happens to me again I will come back here and post why it was.

h57xiucj2z946q

xargs is good for this!

# ps -ef | grep <process string> | awk {' print $2'} | xargs kill

e.g.:

# ps -ef | grep jdk | awk {' print $2'} | xargs kill

or if you wanna be aggressive:

# ps -ef | grep jdk | awk {' print $2'} | xargs kill -9

Hotblack Desiato

syklops wrote: »

Cat blah

ghgh
ghghg
gjgjg
djdjd
eyrytyp

for i in `cat blah`; do echo $i; done

Result:
ghgh
ghghg
gjgjg
djdjd
eyrytyp

Not alot of testing involved. Hence my question.

It'll break if there are spaces in the lines. Not that your PIDs should have spaces

> cat blah
aaaaa
bbbbb
cc cc
ddd d
eeee e
> for i in `cat blah`; do echo $i; done
aaaaa
bbbbb
cc
cc
ddd
d
eeee
e
> while read PID;do echo $PID; done <blah
aaaaa
bbbbb
cc cc
ddd d
eeee e
>

Tom Dunne

syklops wrote: »

Could you not just do killall xrdp?

Wasn't aware of that command, that's exactly what I need. Thanks.

I Just need to be careful not to kill the daemon too.

Khannie

ninja900 wrote: »

It'll break if there are spaces in the lines.

That's the one. Thank you.

syklops

Tom Dunne wrote: »

Wasn't aware of that command, that's exactly what I need. Thanks.

I Just need to be careful not to kill the daemon too.

Presumably(hopefully) the daemon is called xrdpd or something to distinguish it from the clients.

It'll break if there are spaces in the lines. Not that your PIDs should have spaces

Mystery solved, thanks for the input.

niallb

xargs ftw :-)