I'm working on a shell script for a project designed to run in the KornShell (ksh) environment on an AIX system. Part of the script's functionality is to create a directory to store output files. However, given the nature of the script, it's possible it might be run multiple times, and I do not want to trigger an error or create multiple instances of this directory if it already exists.
The conventional method for creating a directory is to use `mkdir`, but as mentioned, this will throw a "File exists" error if the directory is already there. I need a way to either check if the directory exists before attempting to create it, or a method to suppress the error and continue with the script execution without halting the process.
I've considered using `if` statements to check the existence of the directory with `test` or `[`, but I wanted to consult the forum to see if there's a more elegant solution or best practice that I might be overlooking. Here is the basic code that I've come up with:


While the above works, I am curious if there's another recommended method to handle this scenario in ksh. Maybe there's a specific flag for `mkdir` that I am not aware of or a one-liner that can accomplish the same result more efficiently. Any insights or examples would be greatly appreciated.

You can simplify the directory creation process and make your command more idiomatic to ksh by using the `mkdir` command with the `-p` option. This option, which stands for "parents", will create the directory if it does not exist, and will not return an error if it already does. It's a common practice to use this option in scripts to ensure idempotency (the property that a script can be run multiple times without changing the result beyond the initial application).
Here’s how you can use it:


This one-liner is robust and considered good practice when writing scripts where the directory structure may or may not be present already. It eliminates the need for the `if` test and simplifies your code.

That is a much cleaner approach, indeed. The `-p` flag seems to be exactly what I was looking for. It makes the script more readable and efficient. I will incorporate this into my script. Thank you for your suggestion. Below is the updated code with the improvements:


This should maintain the functionality I need while adhering to best practices. I appreciate the concise and helpful response.