Regarding External shell script

I have installed OSMC on raspberry pi 3+ directly without installing Raspbian os.How can I run external user made shell script on raspberry pi? The output of shell script will be input for osmc .

Your question is not really clear. But maybe this is the answer to your question.
Details regarding how to access the command line interface can be found here on our Wiki:

osmc is installed directly on raspberry pi 3+ using the ISO of OSMC.
raspiban os is not installed on raspberry,there is no access to terminal.
Now i want to run my shell script on raspberry pi which gives some output that i want to use as an input for osmc. Is it possible ?
and if it is possible then where to store that shell script and how to run that shell script.
please help me with that.

I have moved you post here as I don’t understand why you opened a new thread. I think I already have answered your questions (even with your new explanation) above.

You can either log in to the console locally or SSH in from another device and access the command line that way. These should both be covered in the link that @fzinken gave you.

The shell script is about checking for external drive at regular time interval and the shell script is giving the output of number of media files present in external drive.
shell script is running at regular interval, If my laptop is not connected through SSH with raspberry pi then it won’t give me the output.So,I want to run shell script in raspberry pi.Is it possible?

Check the link given to you already by @fzinken

You want the pi to run the script itself? Sure that’s possible put the script somewhere on the Pi and use a cron job to run this for you