Why chmod gives "Operation not permitted" error? I try to execute chmod on a file with Termux, but it sends back an error which I'm unable to solve.
My phone is not rooted. If you can help me I would be most grateful to you for this! Here is the command and the error:

$ chmod +x /sdcard/meta-install.sh
chmod: changing permissions of 'meta-install.sh': Operation not permitted


Thanks!
Android does not allow you to create executable files within the sdcard (internal storage, mounted in userspace) partition without root.

A workaround would be to execute the file as bash meta-install.sh, assuming it is a bash file. (Alternatively sh meta-install.sh to run it using sh as the shell).