How to create a .command file with unity with execute previlages?

Hello everyone how do you do,

In my app I'm trying to use ffmpeg through a batch file, windows works great writing .bat files, however when I write .command files on MAC the files don't open and tells me that I don't have permission.

Also when I run the command chmoc u+x [.command File Path] through the terminal the file works..

Knowing that when I create a new text file with the command and rename it to .command it works fine.

I write the command file in unity using File.WriteAll, is there any other way for writing the file that gives the previlage needed? knowing that I run the batch file using a process in unity.

Thank You,