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How to show top five CPU consuming processes with ps?

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159

Why use ps when you can do it easily with the top command?

If you must use ps, try this:

ps aux | sort -nrk 3,3 | head -n 5

If you want something that's truly 'top'esq with constant updates, use watch

watch "ps aux | sort -nrk 3,3 | head -n 5"
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  • 4
    ps aux | sort -k 3,3 | tail -n 5 ;-) Commented May 28, 2011 at 19:01
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    it will be good to include the numeric sort, to skip the header of ps aux. ps aux | sort -nrk 3,3 | head -n 5 Commented May 12, 2016 at 10:42
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    this spawns many processes which is more resource consuming and is also more prone to race condition, because when the piped data comes to head the process list may have already changed Commented Jun 12, 2017 at 9:20
  • This is true @LưuVĩnhPhúc but I wonder how this differs from how top actually works. Commented Jun 15, 2017 at 2:50
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    @icedwater top reads the process list and display the result on its own without piping to any other process Commented Jun 15, 2017 at 3:16
139

The correct answer is:

ps --sort=-pcpu | head -n 6

So you can specify columns without interfering with sorting.

Ex:

ps -Ao user,uid,comm,pid,pcpu,tty --sort=-pcpu | head -n 6

Note for MAC OS X: In Mac OS X, ps doesn't recognize --sort, but offers -r to sort by current CPU usage. Thus, for Mac OS X you can use:

ps -Ao user,uid,comm,pid,pcpu,tty -r | head -n 6
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    This IS the correct answer. Thank you Facundo. I was trying to explain to others that you can use sort and pipe it, but ps also comes built in with an option for sorting and now I see you also use it which is great. Commented Apr 7, 2016 at 16:01
  • The 2nd command appears more useful... but the first one just seems to show bash (x2, or head as well) ps... Commented Jul 3, 2017 at 18:19
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    @Wilf The first one is for highlighting how to sort by cpu consumption without using the command sort, the second one shows how to specify columns without interfering with sorting. When explaining something.. it's always better to be concise and explain one thing at a time. Commented Jul 10, 2017 at 10:29
  • I was asked a question today about why "ps -eo pcpu,pid,comm,pmem | sort -r k1" does not give correct answer since there are some lowest usages on top, but higher ones in the middle. But when I found your answer and try it, I deleted my question since your suggestion worked correctly. Thanks @FacundoVictor. Commented Mar 4, 2022 at 18:01
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I don't think ps is what you are looking for. Have you looked at the output from top?

If you have GNU-Top, try using it's batch mode to spit out a process list sorted by cpu usage and using head/tail to get the top 5 lines (the first 8 are headers):

top -b -n 1 | head -n 12 | tail -n 5

The BSD top seems to behave differently and doesn't have a non-interactive mode, so use one of the other ps based solutions.

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    In OS X, is top -o cpu -n 5 a way of achieving the same thing. Does anyone know? My top is different to your top. Commented May 29, 2011 at 4:00
  • You're the one with the different top so you would be in a position to say. My top doesn't have -o and -n sets the number of times it refreshes the display before quitting. Commented May 29, 2011 at 5:28
  • Fair enough. I'll get on a Linux box this afternoon and take a look. My top doesn't seem to have a batch mode, which is quite limiting. There must be some way of piping top into other commands. I'll do some research. Commented May 29, 2011 at 5:45
  • I mentioned the batch mode switch in my answer but it's actually unnecessary for my top because it auto-detects being part of a pipe instead of an interactive session. Did you try just piping it without that? Commented May 29, 2011 at 5:56
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    Will do. GNU top worked as described this afternoon. Cheers. Commented May 29, 2011 at 12:05
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Depending on your needs you may find this a little more readable:

ps -eo pcpu,pid,user,args --no-headers| sort -t. -nk1,2 -k4,4 -r |head -n 5

sample output:

 1.3 4 root [ksoftirqd/0] 1.1 9 root [ksoftirqd/1] 1.0 17606 nobody /usr/sbin/gmetad 1.0 13 root [ksoftirqd/2] 0.3 17401 nobody /usr/sbin/gmond

(the fields are %CPU,PID,USER,COMMAND)

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  • Just to note the subtle difference here; at least on my system, -o pcpu shows the process's CPU use over its lifetime, not over the last second like ps usually does. There doesn't seem to be any way to get the short-term CPU use using ps -o; it's always just the cpu time the process has used divided by the time the process has been running. Commented Mar 14, 2023 at 13:33
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Quickest one liner I have found for this (note 6 because the header adds up):

ps aux k-pcpu | head -6
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7

In order to add a point to other valuable answers, I prefer:

ps auxk-c | head -6

It also prints the header, which is nice.

Here k is identical to --sort and c specifies CPU usage (alias %cpu) field for sort, while - is for reverse sort.

You may add more specifiers separated by ,, other possible specifiers are : %mem, args, bsdstart, pid, gid, uid ... which you can find full list in STANDARD FORMAT SPECIFIERS section of man page. For example:

 ps auxk -gid,-%mem | head -11

would print 10 processes with highest group id, internally sorted by memory usage.

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5

Note that current versions of ps have sorting ability within them, based on field codes (given in the ps man page). The field code for processor usage is "c". You can use --sort c at the end of a ps command e.g. ps aux --sort c

This will put the process using the most cpu at the bottom of the list. Reverse order of the list by adding a minus to the field code used to sort e.g. ps aux --sort -c

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3

The command line tool ps has its own sort option, so I prefer:

$ ps -eo pcpu,args --sort=-%cpu | head

You can add the columns you want. See what other options are available via the ps man page.

$ man ps
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3

I believe the simplest way to see top 5 cpu consuming process is,

ps -eo pid,comm,%cpu,%mem --sort=-%cpu | head -n 5

To see top 5 memory consuming process is,

ps -eo pid,comm,%cpu,%mem --sort=-%mem | head -n 5

Where,

-e : This flag is used to select all process

-o : This flag is used to format as user-defined.

pid : This argument used for showing pid

comm: This argument used for showing command name only. To get full command use args, cmd or command

%cpu: This argument shows the percentage of cpu utilization of the process in "##.#" format. Here pcpu can also be used.

%mem: This argument shows the ratio of the process's resident set size to the physical memory on the machine, expressed as a percentage. Here pmem can also be used.

--sort: Specify sorting order. After = the - sign is used to sort highest value at the top where the default option which is + is to list increasing numerical order [i.e 0 to n].

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3

Here is something I came up with as I found the original answer a bit too arcane. so, for bare bones, type 

ps -e -o pid,cmd,%cpu,%mem --sort=-%cpu | head -n 6

Let's understand what each does. ps ofcourse shows a snapshot of current processes. -e shows every process on the system -o is to define the format we want the result in, as you can see we have specified the format as pid,cmd,%cpu,%mem, next --sort ofcourse, sorts. One important point to note here is that by default it sorts ascending. Also --sort needs the parameter to sort by, which we provide by -%cpu notice the - this is so that it sorts descending and we get the highest CPU usage first. Then we pipe this into head -n 6 which gives us the this

 PID CMD %CPU %MEM 5995 transmission-gtk 5.1 1.3 402083 /usr/lib64/firefox/firefox 4.2 6.7 978875 /usr/lib64/firefox/firefox 3.6 4.0 2982 /usr/bin/gnome-shell 2.7 3.0 2774 /usr/libexec/Xorg vt2 -disp 1.9 1.0

Now that we understand the basics we can show off a little. For example you can use watch to update the list every 2 seconds like this 

watch "ps -e -o pid,cmd,%cpu,%mem --sort=-%cpu | head -n 6"

Or, for something fancier, you can install a python package called tabulate, type this in your terminal pip install tabulate, now you can really show off, using some sed fu etc

 ps -e -o pid,cmd,%cpu,%mem --sort=-%cpu | head -n 5 | tabulate -1 -f github | cut -f 2- -d "|" | sed '2s/----/ /'

which gives this beautiful output -

 | PID | CMD | %CPU | %MEM | |--------|----------------------------|--------|--------| | 5995 | transmission-gtk | 5.1 | 1.3 | | 978875 | /usr/lib64/firefox/firefox | 4.5 | 4.1 | | 402083 | /usr/lib64/firefox/firefox | 4.2 | 6.7 | | 2982 | /usr/bin/gnome-shell | 2.7 | 3 |

for ease of use and avoid typing this command over and over you can alias them into your .bashrc like this

alias top5="ps -e -o pid,cmd,%cpu,%mem --sort=-%cpu | head -n 6"

after doing source .bashrc you can just type top5. Or, you can just use htop and sort by %CPU htop also allows you to kill processes and much more.

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0

top on Mac OS X has a logging mode option in the form of top -l numberOfSamples (which seems to be the equivalent to the batch mode of GNU top). It is necessary, though, to have at least two samples because "the first sample displayed will have an invalid %CPU displayed for each process, as it is calculated using the delta between samples" (man 1 top).

# examples top -o cpu -l 2 -n 5 | tail -n 6 top -o cpu -l 2 -n 5 -stats pid,command,cpu | tail -n 6 top -o cpu -l 2 -n 5 -stats pid,command,cpu -U $(logname) | tail -n 6
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0

top will display what is using your CPU. If you have it installed, htop allows you more fine-grained control, including filtering by—in your case—CPU.

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-2

top -bn1 |sed -n '7,12'p works as a nice little one liner too.
Though I do prefer to use ps with the --sort=X -o X,Y,Z

using ps you can pull different stats grep for a process OR user and then total OR avg them with a pipe to awk.

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