I would like to monitor one process's memory / cpu usage in real time. Similar to top but targeted at only one process, preferably with a history graph of some sort.

  • What memory statistics do you want? There are lots of them.
    – vwduder
    Jan 13, 2011 at 11:33
  • Memory usage over a given time frame, current usage, maximum usage, average.
    – Josh K
    Jan 13, 2011 at 11:33
  • Multiple solutions all good.
    – Cymatical
    Aug 31, 2022 at 20:39

15 Answers 15


On Linux, top actually supports focusing on a single process, although it naturally doesn't have a history graph:

top -p PID

This is also available on Mac OS X with a different syntax:

top -pid PID
  • 15
    And since you may not want to look up the PID every time, try something like top -p `pgrep -f /usr/bin/kvm`. Aug 17, 2010 at 3:33
  • I use Cacti to monitor some individual processes, but installing a full blown Cacti installation sounds too complex for the simple situation asked here. Aug 17, 2010 at 3:34
  • @Stefan: I'm assuming I would have to run that remotely?
    – Josh K
    Aug 17, 2010 at 4:00
  • @Josh : Yes you would need to run Cacti (Which requires MySQL, Apache and few other packages) on another server. On most distros, it's pretty simple to install using Yum or apt-get. Aug 17, 2010 at 20:48
  • @Stefan if you want to to check remotly you can do ssh@remotehost 'top -p PID > ~hostname_pid.txt; exit'and
    – klerk
    May 13, 2014 at 20:02


2020 update (Linux/procfs-only). Returning to the problem of process analysis frequently enough and not being satisfied with the solutions I described below originally, I decided to write my own. It's a pure-Python CLI package including its couple of dependencies (no heavy Matplotlib), can potentially plot many metrics from procfs, JSONPath queries to the process tree, has basic decimation/aggregation (Ramer-Douglas-Peucker and moving average), filtering by time ranges and PIDs, and a couple of other things.

pip3 install --user procpath

Here's an example with Firefox. This records all processes with "firefox" in their cmdline (query by a PID would look like '$..children[?(@.stat.pid == 42)]') 120 times one time per second.

procpath record -i 1 -r 120 -d ff.sqlite '$..children[?("firefox" in @.cmdline)]'

Plotting RSS and CPU usage of a single process (or several) out of all recorded would look like:

procpath plot -d ff.sqlite -q cpu -p 123 -f cpu.svg
procpath plot -d ff.sqlite -q rss -p 123 -f rss.svg

Charts look like this (they are actually interactive Pygal SVGs):



The following addresses history graph of some sort. Python psrecord package does exactly this.

pip install psrecord                             # local user install
sudo apt-get install python-matplotlib python-tk # for plotting; or via pip

For single process it's the following (stopped by Ctrl+C):

psrecord $(pgrep proc-name1) --interval 1 --plot plot1.png

For several processes the following script is helpful to synchronise the charts:

psrecord $(pgrep proc-name1) --interval 1 --duration 60 --plot plot1.png &
psrecord $(pgrep proc-name2) --interval 1 --duration 60 --plot plot2.png &
wait $P1 $P2
echo 'Done'

Charts look like: psrecord example


The package provides RSS-only sampling (plus some Python-specific options). It can also record process with its children processes (see mprof --help).

pip install memory_profiler
mprof run /path/to/executable
mprof plot

By default this pops up a Tkinter-based (python-tk may be needed) chart explorer which can be exported:


graphite-stack & statsd

It may seem an overkill for a simple one-off test, but for something like a several-day debugging it's, for sure, reasonable. A handy all-in-one raintank/graphite-stack (from Grafana's authors) image and psutil and statsd client. procmon.py provides an implementation.

$ docker run --rm -p 8080:3000 -p 8125:8125/udp raintank/graphite-stack

Then in another terminal, after starting target process:

$ sudo apt-get install python-statsd python-psutil # or via pip
$ python procmon.py -s localhost -f chromium -r 'chromium.*'

Then opening Grafana at http://localhost:8080, authentication as admin:admin, setting up datasource https://localhost, you can plot a chart like:

grafana chart

graphite-stack & telegraf

Instead of Python script sending the metrics to Statsd, telegraf (and procstat input plugin) can be used to send the metrics to Graphite directly.

Minimal telegraf configuration looks like:

  interval = "1s"

  servers = ["localhost:2003"]
  prefix = "testprfx"

  pid_file = "/path/to/file/with.pid"

Then run line telegraf --config minconf.conf. Grafana part is the same, except metrics names.


pidstat (part of sysstat package) can produce output that can be easily parsed. It's useful in case when you need extra metrics from the process(es), e.g. most useful 3 groups (CPU, memory and disk) contain: %usr, %system, %guest, %CPU, minflt/s, majflt/s, VSZ, RSS, %MEM, kB_rd/s, kB_wr/s, kB_ccwr/s. I described it in a related answer.

  • pgrep systemd is giving multiple lines of output, and thus bugs the psrecord, what should be done? I just want to test with any process.
    – EralpB
    Apr 11, 2018 at 7:09
  • 1
    @EralpB pgrep --help to the rescue. There's at least --newest and --oldest.
    – saaj
    Apr 11, 2018 at 9:03
  • 2
    This should be the accepted answer, since it actually gives a memory usage history plot. Note for the psrecord method, Ctrl+C on the psrecord process just quits without saving a plot, you need to end the process-under-test. Jan 26, 2019 at 3:03
  • 1
    psrecord worked well, thank you. To get it to work on a server without a GUI (X11) I had to configure matplotlibrc as described in stackoverflow.com/a/37605654/3018750
    – rkok
    Oct 25, 2019 at 4:52
  • 4
    A simple one-liner if you want to run a command and profile it with psrecord right away: my-command & psrecord $! --interval 1 --plot plot1.png. $! returns the PID of the last executed command, so you don't need to pgrep. And using a single & runs my-command detached, meaning that the shell won't wait for it to finish before running psrecord.
    – Gus
    Dec 4, 2019 at 2:27

htop is a great replacement to top. It has… Colors! Simple keyboard shortcuts! Scroll the list using the arrow keys! Kill a process without leaving and without taking note of the PID! Mark multiple processes and kill them all!

Among all the features, the manpage says you can press F to follow a process.

Really, you should try htop. I never started top again, after the first time I used htop.

Display a single process:

htop -p PID
  • 7
    +1 for htop. This is one of the first program I install on a new system. It makes my life much easier. The tree view is also very handy.
    – Barthelemy
    Nov 24, 2010 at 12:22
  • 10
    top also has colors. Press z.
    – tshepang
    Jan 12, 2011 at 1:41
  • 2
    You're right! top has colors! Too bad its colors are quite useless, specially when compared to htop (which fades other users processes and highlights the program basename). Jan 12, 2011 at 18:17
  • 1
    top can also kill processes without leaving. Just hit k. Jul 19, 2012 at 13:57
  • 2
    And htop -p PID will work too, just like the example given by @Michael Mrozek.
    – noisebleed
    Nov 25, 2014 at 12:05

Using top and awk one could easily create e.g. a comma separated log of %CPU ($9) + %MEM ($10) usage that can later be fed into any statistics and graphing tool.

top -b -d $delay -p $pid | awk -v OFS="," '$1+0>0 {
print strftime("%Y-%m-%d %H:%M:%S"),$1,$NF,$9,$10; fflush() }'

Output will be like

2019-03-26 17:43:47,2991,firefox,13.0,5.2
2019-03-26 17:43:48,2991,firefox,4.0,5.2
2019-03-26 17:43:49,2991,firefox,64.0,5.3
2019-03-26 17:43:50,2991,firefox,71.3,5.4
2019-03-26 17:43:51,2991,firefox,67.0,5.4

This won't give good results for large $delay, though, because the printed timestamp is actually $delay behind due to how top's output works. Without going into too much detail, 1 simple way around this is to log the time provided by top:

top -b -d $delay -p $pid | awk -v OFS="," '$1=="top"{ time=$3 }
$1+0>0 { print time,$1,$NF,$9,$10; fflush() }'

Then the timestamp is accurate, but output will still be delayed by $delay.


To use that information on a script you can do this:


nTimes=10; # customize it
delay=0.1; # customize it
strCalc=`top -d $delay -b -n $nTimes -p $nPid \
  |grep $nPid \
  |sed -r -e "s;\s\s*; ;g" -e "s;^ *;;" \
  |cut -d' ' -f9 \
  |tr '\n' '+' \
  |sed -r -e "s;(.*)[+]$;\1;" -e "s/.*/scale=2;(&)\/$nTimes/"`;
nPercCpu=`echo "$strCalc" |bc -l`
echo $nPercCpu

use like: calcPercCpu.sh 1234 where 1234 is the pid

For the specified $nPid, it will measure the average of 10 snapshots of the cpu usage in a whole of 1 second (delay of 0.1s each * nTimes=10); that provides a good and fast accurate result of what is happening in the very moment.

Tweak the variables to your needs.

  • 2
    Uhm, 10 processes to monitor the cpu usage of 1?
    – xebeche
    Mar 13, 2019 at 14:19
  • @xebeche "it will measure the average of 10 snapshots" "nTimes=10; # customize it" :) Mar 19, 2019 at 22:55
  • 1
    I meant I don't like the fact that you call 10 processes to retrieve 1 number ($nPercCpu): shell, top, grep, sed, cut ... bc. Many if not all of these you could for instance merge into 1 Sed or Awk script.
    – xebeche
    Mar 19, 2019 at 23:29
  • @xebeche cool, feel free to edit adding a better command to the existing one (as an alternative), you got my curiosity :) Mar 24, 2019 at 1:03
  • 2
    I've added my own answer. BTW, note that there is no point in calculating an average because top's output is an average over $delay. Cf. How to calculate the CPU usage
    – xebeche
    Mar 26, 2019 at 17:12


Show CPU statistics at a 2-second interval for 2 times, of PID 7994:

pidstat -p 7994 2 2

03:54:43 PM   UID       PID    %usr %system  %guest    %CPU   CPU  Command
03:54:45 PM     0      7994    1.50    1.50    0.00    3.00     1  AliYunDun
03:54:47 PM     0      7994    1.00    1.00    0.00    2.00     0  AliYunDun


# Show page faults and memory utilization:
pidstat -r

# Show input/output usage per process id:
pidstat -d

# Show information on a specific PID:
pidstat -p PID

# Show memory statistics for all processes whose command name include "fox" or "bird":
pidstat -C "fox|bird" -r -p ALL

I'm a bit late here but I'll share my command line trick using just the default ps

WATCHED_PID=$({ command_to_profile >log.stdout 2>log.stderr & } && echo $!);
while ps -p $WATCHED_PID --no-headers --format "etime pid %cpu %mem rss"; do 
   sleep 1 

I use this as a one-liner. Here the first line fires the command and stores the PID in the variable. Then ps will print the elapsed time, the PID the percent CPU using, the percent memory, and the RSS memory. You can add other fields as well.

As soon as the process ends, the ps command won't return "success" and the while loop will end.

You can ignore the first line if the PID you want to profile is already running. Just place the desired id in the variable.

You'll get an output like this:

  00:00  7805  0.0  0.0  2784
  00:01  7805 99.0  0.8 63876
  00:02  7805 99.5  1.3 104532
  00:03  7805  100  1.6 129876
  00:04  7805  100  2.1 170796
  00:05  7805  100  2.9 234984
  00:06  7805  100  3.7 297552
  00:07  7805  100  4.0 319464
  00:08  7805  100  4.2 337680
  00:09  7805  100  4.5 358800
  00:10  7805  100  4.7 371736

I normally use following two :

  1. HP caliper : its very good tool for monitoring processes it you can check call graph and other low level information also. But please note its free only for personal use.

  2. daemontools : a collection of tools for managing UNIX services

  • 7
    I used daemontools for years. It's great as a supervisor/watchdog for other processes. How does it help you monitor CPU/memory usage for one process? Aug 19, 2010 at 4:05

If you have a cut-down Linux distribution where top does not have per process (-p) option or related options, you can parse the output of the top command for your process name to get the CPU usage information per process.

while true;  do top -bn1 | awk '/your_process_name/ {print  $8}' ; sleep 1; done

8 represents the CPU usage per process in the output of the top command in my embedded Linux distribution

  • I found this usefull as it track process name not pid, as for something like fail2ban-client the pid changes each time it runs, i had to change column $8 to $9 Jan 11 at 1:09

If you know process name you can use

top -p $(pidof <process_name>)
  • 12
    That's pretty much what the accepted answer, from years ago, and its first comment say.
    – dhag
    Apr 29, 2015 at 15:26

Not enough reputation to comment, but for psrecord you can also call it directly, in a programmatic way, directly in Python:

from psrecord.main import monitor
monitor(<pid number>, logfile = "./test.log", plot="./fig.png", include_children=True)

MacOS solution to create the following graph

plotted data of process cpu consumption

# Install dependencies
brew install gnuplot libmagic 

# Sample process. Replace 1234 with process ID
while :;do ps -p 1234 -o %cpu= >> procdata.txt;sleep 1;done

# Plot
gnuplot<<<'set term png;set output "procplot.png";plot "procdata.txt" with boxes'

Launch a program and monitor it

This form is useful if you want to benchmark an executable easily:

topp() (
  if [ -n "$O" ]; then
    $* &
    $* &>/dev/null &
  trap "kill $pid" SIGINT
  printf '%s\n' "$o"
  while s="$(ps --no-headers -o "$o" -p "$pid")"; do
    printf "$i $s\n"
    i=$(($i + 1))
    sleep "${T:-0.1}"


topp ./myprog arg1 arg2

Sample output:

0  0.0  0.0 177584
1  0.0  0.1 588024
2  0.0  0.1 607084
3  0.0  0.2 637248
4  0.0  0.2 641692
5 68.0  0.2 637904
6 80.0  0.2 642832

where vsz is the total memory usage in KiB, e.g. the above had about 600MiB usage.

If your program finishes, the loop stops and we exit topp.

Alternatively, if you git Ctrl + C, the program also stops due to the trap: https://stackoverflow.com/questions/360201/how-do-i-kill-background-processes-jobs-when-my-shell-script-exits

The options are:

  • T=0.5 topp ./myprog: change poll interval
  • O=1 topp ./myprog: don't hide program stdout/stderr. This can be useful to help correlate at which point memory usage bursts with stdout.

ps vs top on instantaneous CPU% usage

Note that the CPU usage given by ps above is not "instantaneous", but rather the average over the processes' lifetime as mentioned at: Top and ps not showing the same cpu result

That thread as well as: https://stackoverflow.com/questions/1332861/how-can-i-determine-the-current-cpu-utilization-from-the-shell/1332955#1332955 suggest that the Linux kernel does not store any more intermediate usage statistics, so the only way to do that would be to poll and calculate for the previous period, which is what top does.

We could therefore use top -n1 instead of ps if we wanted that:

toppp() (
  $* &>/dev/null &
  trap exit SIGINT
  top -b n1 -d "${T:-0.1}" -n1 -p "$pid"
  while true; do top -b n1 -d "${T:-0.1}" -n1 -p "$pid"  | tail -1; printf "$i "; i=$(($i + 1)); done

as mentioned e.g. at: https://stackoverflow.com/a/62421136/895245 which produces output of type:

top - 17:36:59 up  9:25, 12 users,  load average: 0.32, 1.75, 2.21
Tasks:   1 total,   1 running,   0 sleeping,   0 stopped,   0 zombie
%Cpu(s): 13.4 us,  2.5 sy,  0.0 ni, 84.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
MiB Mem :  31893.7 total,  13904.3 free,  15139.8 used,   2849.7 buff/cache
MiB Swap:      0.0 total,      0.0 free,      0.0 used.  16005.5 avail Mem

    PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND
 706287 ciro      20   0  590436  40352  20568 R 106.7   0.1   0:00.16 node
 706287 ciro      20   0  607060  57172  21340 R 126.7   0.2   0:00.35 node
1  706287 ciro      20   0  642008  80276  21812 R 113.3   0.2   0:00.52 node
2  706287 ciro      20   0  641676  93108  21812 R 113.3   0.3   0:00.70 node
3  706287 ciro      20   0  647892  99956  21812 R 106.7   0.3   0:00.87 node
4  706287 ciro      20   0  655980 109564  21812 R 140.0   0.3   0:01.09 node

Some related threads:

My only problems with this is that top is not as nice for interactive usage:

  • Ctrl + C does not exit the above command, not sure why trap exit is not working as it does with ps. I have to kill the command Ctrl + \, and then that does not kill the process itself which continues to run on the background, which means that if it is an infinite loop like a server, I have to ps aux and then kill it.
  • the not exit automatically when the benchmarked program exits

Maybe someone more shell savvy than me can find a solution for those.


Tested on Ubuntu 21.10.


If you need the averages for a period of time of a specific process, try the accumulative -c option of top:

top -c a -pid PID

"-c a" found in top for Mac 10.8.5.

For Scientific Linux, the option is -S, that can be set interactively.

  • 1
    You'll likely want to add further details around which version(s) of top actually provide this feature. My version on Fedora 19 does not. Same too on Ubuntu 13.04.
    – slm
    May 12, 2014 at 1:22
  • 1
    You're right!, I was so happy of having found something useful, I forgot I was in my mac at home.
    – Kieleth
    May 13, 2014 at 19:34

Monitoring memory usage is something I frequently need when testing C++ apps. I used the solutions already provided in the previous answers and I also wrote a little app for myself and I made it available here in case anyone else needs it in the future: https://github.com/carlonluca/procweb.

It is a binary written in Rust (there is also a version written in Qt in the repo) that monitors a process by sampling RAM/IO/CPU etc... The binary also starts a web server to let the user inspect data:


The binary stores all the samples, the chart range and scale can be tuned, you can download a CSV and the chart itself. Data is kept in memory until the sampler process is killed.

Can be installed through Cargo: cargo install procweb-rust. Static binaries for x64, arm64 and armhf can also be downloaded from the GitHub repo.

More info here.

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