I'm looking for somthing like top is to CPU usage. Is there a command line argument for top that does this? Currently, my memory is so full that even 'man top' fails with out of memory :)
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1http://theunixshell.blogspot.in/2012/12/blog-post.html – Vijay Apr 17 '14 at 19:11
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Thanks @Vijay , that one also worked on Solaris 9 flawlessly. – saulius2 Apr 30 '20 at 14:29
11 Answers
From inside top
you can try the following:
- Press SHIFT+f
- Press the Letter corresponding to %MEM
- Press ENTER
You might also try:
$ ps -eo pmem,pcpu,vsize,pid,cmd | sort -k 1 -nr | head -5
This will give the top 5 processes by memory usage.

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23Under Linux, simply press
M
to sort by physical memory usage (RES column). Under *BSD, runtop -o res
ortop -o size
. But htop is a lot nicer and doesn't even consume more memory than top (however it's not part of the basic toolset so you might not have it installed). – Gilles 'SO- stop being evil' Dec 19 '10 at 13:38 -
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@Steven How can we group process with same parent? Basically firefox shows up in multiple times may be as it spawns multiple child processes. Is it possible to get combined memory usage? – Porcupine Mar 07 '21 at 21:45
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1
$ top
-bash: fork: Cannot allocate memory
- In case anyone else appreciates this
If you have it installed I like htop
once launching it you can press f6, down arrow (to MEM%
), enter to sort by memory.

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In Solaris the command you would need is:
prstat -a -s size
This will list all processes in order of descending process image size. Note that the latter is based on memory committed to the process by the OS, not its resident physical memory usage.
There are supposedly versions of "top" available for Solaris, but these are not part of the standard installation.

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Once top
starts, press F to switch to the sort field screen. Choose one of the fields listed by pressing the key listed on the left; you probably want N for MEM%

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2If you want MEM%, pressing 'M' does the same stated above. 'c' adds command line parameters to the process list, may be informative for your problem. – wag Dec 19 '10 at 08:46
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This command will identify the top memory consuming processes:
ps -A --sort -rss -o pid,pmem:40,cmd:500 | head -n 6 | tr -s " " ";z"
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Doesn't work on Solaris 9:
ps: illegal option -- - ps: ort is an invalid non-numeric argument for -s option ps: illegal option -- r ps: s is an invalid non-numeric argument for -s option ps: unknown output format: -o pmem:40 ps: unknown output format: -o cmd:500
– saulius2 Apr 30 '20 at 14:22
One nice alternative to top
is htop
. Check it, it is much more user friendly than regular top.

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It can be achieved in multiple ways, My favourite one is:
The PS way:
[arif@arif ~]$ ps -eo pid,cmd,%cpu,%mem --sort=-%mem
Where,
-e
: to select all process-o
: to apply to the output formatpid
,cmd
,%cpu
,%mem
: Output format in exact order. Here,pcpu
andpmem
can be used instead of%cpu
and%mem
.- But sadly (don't know why) it doesn't work on some machine (Oracle Linux) and some older machine. You can use the following similar alternatives.
[arif@arif ~]$ ps aux --sort '-%mem' --cols 120 | head
Where,
--cols 100
: to specify column width of the output as sometimescmd
gets very long. This is not necessary if you don't want curtailed commands with arguments.aux
: to see every process on the system using BSD syntax
[arif@arif ~]$ ps -eo pid,cmd,%cpu,%mem --sort -rss
Where,
-rss
: resident set size, the non-swapped physical memory that a task has used
[arif@arif ~]$ ps aux --sort -rss --cols 120
The top way:
[arif@arif ~]$ top -b -o +%MEM
Where,
-b
: to usetop
asbatch
mode.-o
: to override sort fieldname followed by a fieldname%MEM
And you can always use head
and/or tail
to control the output.

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Doesn't work on Solaris 9. The
top
cmd-lines gives:top: '+%MEM' is not a recognized sorting order. Try one of these: cpu size res time
– saulius2 Apr 30 '20 at 14:25
Globally: It's always recommended to use a log analyser tool for logging history logs such as Splunk, ELK etc. So that using query language you can easily get the PIDs and its usage by CPU & memory.
AT SERVER/OS LEVEL: From inside top you can try the following:
Press SHIFT+M ---> This will give you a process which takes more memory in descending order.
You might also try:
$ ps -eo pid,ppid,cmd,%mem,%cpu --sort=-%mem | head -10
This will give the top 10 processes by memory usage. Also you can use vmstat utility to find the RAM usage at same time not for history.

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This alias works nice for me in a bash shell:
alias mtop='{ echo "Mem% PID Binary"; ps -A --sort -rss -o pid,pmem:40,cmd:500 | tail -n +2 | head -n 10 | tr -s " " | sed -r "s/^\s*([0-9]+) ([0-9.]+) ([a-zA-Z/]+).*$/\2 \1 \3/"; } | column -t -s " "'
This will print out a neat list of processes sorted by memory consumption:
-=# mtop
Mem% PID Binary
22.9 528235 /opt/intellij
5.4 906569 /usr/share/elasticsearch/jdk/bin/java
3.7 544512 /usr/bin/node
2.2 986170 /usr/lib/firefox/firefox
1.9 795138 /usr/bin/node
1.1 795188 /usr/bin/node
1.0 747819 /usr/lib/jvm/java
0.9 599 /usr/bin/pipewire
0.7 414 /usr/lib/Xorg
0.7 544536 /usr/bin/node

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On macOS, ps
does not support the --sort
option.
You can use the BSD-only -m
flag to sort by "memory usage," which avoids piping all rows through sort
. (The ps
man page doesn't specify exactly which "memory usage" metric is used.)
ps -m -aexo pmem,rss,vsize,pid,etime,user,args | head
Or, if you want sorting by CPU: you can use the BSD-only -r
flag to sort by cpu usage.
ps -r -aexo pcpu,cputime,pid,etime,user,args | head

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@Ternvein good point, I copied the wrong snippet from my debugging notes ;) Added memory too now. – Carl Walsh Jul 20 '23 at 20:16