How can I measure how much CPU and RAM has been used by a command?

I'm trying to measure the memory of a process that I call via the command line (i.e., I want to find out much CPU/RAM the process takes). Is there any command that I can add to the command calling the process that will achieve this?

`top`

Example of firefox. Find the PID:

ps -aux | grep -i firefox

Then you can use top -p pid:

top -p  3845

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`ps`

You can also use ps command, firefox pid is 3845

$ ps -p 3845 -o %cpu,%mem,cmd
%CPU  %MEM CMD
11.1  3.7 /usr/lib/firefox/firefox

I am not satisfied with the above mentioned commands, and I found something that you should be interested in.

Monit

sudo apt-get install monit -y

Edit the Monit Config File

sudo nano /etc/monit/monitrc

Enable the web interface

set httpd port 2812
# use address localhost # only accept connection from localhost
allow localhost # allow localhost to connect to the server and
# allow 192.168.1.0/255.255.255.0 # allow any host on 192.168.1.* subnet
allow admin:monit # require user 'admin' with password 'monit'

Checking process every 2 secons

## Start Monit in the background (run as a daemon):
set daemon 120 to only 2  # check process every 2 sec

Example Firefox

In the end copy paste the following command

check process firefox
matching "firefox"

Save and Exit

Check your syntax

Fix any problems found – it’s not too tough to figure out what’s going on.

sudo monit -t

Start (or restart) Monit

sudo service monit start

Visit the web interface

http://localhost:2812 if you’re running Ubuntu Desktop, or

Click on Firefox

How to Install Monit
Monit: check process without pidfile
Monit FAQ
Real-world Monit configuration examples
How can I get the CPU usage and memory usage of a single process on Linux (Ubuntu)?

You can also use these links for help and modify your process.

UPDATE

You can also configure an alert if firefox uses more than 250 MB of ram

check process firefox
matching "firefox"
if totalmem > 250.0 MB for 1 cycles then alert

You can also execute command

if totalmem > 250.0 MB for 1 cycles then exec "path to script"

You can also make a script of Notify-Send

/usr/bin/notify-send firefox "More Than 250 MB OF RAM"

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The GNU time command can print the maximum resident set size used by a command. You do have to make sure to use the /usr/bin/time command, not the Bash Shell built-in time keyword.

For an example to measure the firefox command:

/usr/bin/time --format="Size:%MK  Cpu:%P  Elapsed:%e" firefox &

After using firefox a while, I close it out to get the report:

Size:168644K  Cpu:30%  Elapsed:226.34

While it is possible to use the TIME environment variable to set the default format I've found it more flexible to set up individual bash aliases with specific formats. So for the above I would add to my ~/.bash_aliases file:

alias ztm="/usr/bin/time --format=\"Size:%MK  Cpu:%P  Elapsed:%e\""

So that from my Bash Shell I could just enter:

ztm firefox &

References:

man time
info time
man 2 getrusage # - Shows which measures are available on Linux, the others show as zero