Scripting with unix to get the processes run by users [closed] - linux

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If I find out I have two users logged (UserA and UserB) in to the systems right now, How do i find out the processes run by those two users. but, the trick here is the script is to be run in an unattended batch without any input from the keyboard. other than being invoked.
I know the first part of the script would be
who | awk '{print $1}'
the output of this would be
UserA
UserB
What I would like to know is, how can I use this output and shove it with some ps command automatically and get the required result.

Answer 1

I finally figured out the one-liner I was searching for, with the help of the other answers (updated for case where no users logged in - see comments).
ps -fU "`who | cut -d' ' -f1 | uniq | xargs echo`" 2> /dev/null
The thing inside the backticks is executed and "inserted at the spot". It works as follows:
who : you know what that does
cut -d' ' : split strings into fields, using ' ' as separator
-f1 : and return only field 1
uniq : return only unique entries
xargs echo : take each of the values piped in, and send them through echo: this strips the \n
2> /dev/null : if there are any error messages (sent to 2: stderr)
: redirect those to /dev/null - i.e. "dump them, never to be seen again"
The output of all that is
user1 user2 user3
...however many there are. And you then call ps with the -fU flags, requesting all processes for these users with full format (you can of course change these flags to get the formatting you want, just keep the -U in there just before the thing in "` `"
ps -fU user1 user2 user3

Answer 2

Get a list of users (using who), save to a file, then list all processes, and grep that (using the file you just created),
tempfile=/tmp/wholist.$$
who | cut -f1 -d' '|sort -u > $tempfile
ps -ef |grep -f $tempfile
rm $tempfile

Answer 3

LOGGED_IN=$( who | awk '{print $1}' | sort -u | xargs echo )
[ "$LOGGED_IN" ] && ps -fU "$LOGGED_IN"
The standard switch -U will restrict output to only those processes whose real user ID corresponds to any given as its argument. (E.g., ps -f -U "UserA UserB".)

Answer 4

Not sure if I'm understanding your question correctly, but you can pipe the output of ps through grep to get the processes run by a particular user, like so:
ps -ef | grep '^xxxxx '
where xxxxx is the user.