Script to get user that has process with most memory usage? - linux

Question

How can I write a script that gives an output of the user that has the process with the most memory usage in the system. The script is sh. I tried to use top command as the starting point but it seems it does not work with pipes because it continues running until it is quit.

Answer 1

If you just want the user name of the process using the most memory, try something like:
$ ps axho user --sort -rss | head -1
This checks the resident memory size rss of the processes. If you'd rather check the whole virtual size, use vsz instead of rss. If you want percentage of resident memory used, use pmem (but this could change from moment to moment due to the scheduler, and may not pull out the biggest memory hog). If you'd rather have the user ID instead of user name, use uid instead of user.
The ps options are:
ax for "all processes" (everybody)
h for "no header" in output
o to specify the output format: user (user name)
--sort -rss sort by rss (descending order)
The head -1 strips out all but the first line (which has the largest rss since it's in descending order).
It might be useful to get not just the user name, but some more information about the process, like:
$ ps axho user,pid,rss --sort -rss | head -1
This gives the user name, process ID, and resident memory usage of the top process, all on one line. You could pull out the values individually in whatever script you use it in.

Answer 2

this works in centos: list most memory cost process
[root#182 ~] # ps aux | sort -k 4 -r | head -n2
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 7048 0.2 9.6 8060236 1573612 ? Ssl Dec14 8:23 java -Djava.security.e
sort -k 4 : sort by the forth column, my pc column4 = %MEM
in other linux/unix, you may find the right column number for memory

Answer 3

if you're allowed to use only top, this can be a solution:
top -o VIRT -n 1 | head -8 | tail -1 | cut -d ' ' -f 5
top -o VIRT allows you to override sorting by default column and sort it by column VIRT
top -n 1 allows you to limit iterations that top will make before exiting. We need only one iteration - it's like when you take a photo while recording a video - you saved info at a particular moment
| head -8 allows you to output only first 8 lines of previous output/ Why 8? It's because top is displaying a lot of info before displaying the table with processes:
we don't need all these lines
Tasks: 247 total, 1 running, 245 sleeping, 0 stopped, 1 zombie
%Cpu(s): 5,9 us, 1,5 sy, 0,0 ni, 92,6 id, 0,0 wa, 0,0 hi, 0,0 si, 0,0 st
MiB Mem : 15698,4 total, 7256,4 free, 3087,8 used, 5354,2 buff/cache
MiB Swap: 18222,0 total, 18222,0 free, 0,0 used. 11441,1 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
6249 mneznaev 20 0 46,5g 287484 110232 S 0,0 1,8 5:40.11 code
| tail -1 allows you to get the last line of previous 8 lines that we got by previous step with head and now we have:
6249 mneznaev 20 0 46,5g 290332 110232 S 0,0 1,8 5:40.27 code
cut -d ' ' -f 5 allows you to separate file by columns, where -d ' ' is an option that defines space as a separator and -f 5 allows you to get the 5th column/ Why 5th? That's because there are some spaces before the actual value of PID (before 6249 in my case) and first 3 columns after cut by space are empty. And the 5th column is a username:
mneznaev#mneznaev-desktop:~$ top -o VIRT -n 1 | head -8 | tail -1 | cut -d ' ' -f 5
mneznaev
That's it. Hope it was helpful