How can I write a shell script that shows the results in real time?
Something like the
top command that updates the results after some fixed intervals of time.
Unix & Linux Stack Exchange is a question and answer site for users of Linux, FreeBSD and other Un*x-like operating systems. It only takes a minute to sign up.Sign up to join this community
you can use the watch(1) command to run your script at regular intervals:
watch -n 1 myscript.sh
This will run
myscript.sh every 1 second clearing the screen between each run and with a timestamp in the corner. You can use the
-d option and it will even highlight differences in the output per run.
Most of that data is generally exposed in the /proc virtual file-system primitives. Each process has an entry in /proc in a directory called the PID. So /proc/5437 would have the primitives for the 5437 process. Reading the primitives there and parsing appropriately would yet you close to what top does.
Top actually works by calling specific function calls that extract this information directly from the kernel instead of pulling it from files. To do the same from bash you'd have to either pull it from the /proc virtual file system, or extract it out of other calls such as to
As for real-time, that isn't quite doable at the level of detail top provides. You can slice time fine enough that it appears to be real-time, but you will still be getting time-slices.
Erm, in case you're looking at
top output for a longer time, and not just to check if a program is doing fine, I suggest using htop.
It give's you a lot of real time information and is easier to control and manage.
You can change the layout of the output, such as bar graphs and columns.
top uses Curses and reads the
/proc file system