How to capture the output of a top command in a file in linux?

Question

I want to write the output of a specific \'top\' command to a file. I did some googling and find out that it can be done by using the following command.

top         


        

Answer 1

I had the exact same problem...

here was my line:

top -b -u myUser | grep -v Prog.sh | grep Prog > myFile.txt

It would create myFile.txt but it would be empty when I Ctrl+C'd it. So after I kicked off my top command, then I started a SECOND top process. When I found the first top's PID (took some trial and error), and I killed it thru the second top, the first top wrote to the file as expected.

Hope that helps!

Answer 2

If you wish to run the top command in background (just not to worry about logout/sleep, etc) - you can make use of nohup or batch job or cron or screen.

Using nohup (stands for : No Hang Up):

Say suppose if you save the top command in a file called top-exec.sh with following content :

 top -p <PID> -b > /tmp/top.log

You can replace the top command for whatever process you are interested in. Then, You can execute top-exec.sh using nohup as follows :

$> nohup top-exec.sh &

This will redirect all the output of top command to a file named "top.log".

Answer 3

Here is the 1-liner I like to use on my mac:

top -o -pid -l 1 | grep "some regexp"

Cheers.

Answer 4

It looks like the output is not writing to the file until all iterations are finished. You could solve this by wrapping with an external loop like this:

touch top-output.txt
while true; do
    top -b | grep init >> top-output.txt
done