Editing Comparison of command shells (section)

=== Execute permission ===
Some operating systems define an ''execute'' permission which can be granted to users/groups for a file when the [[file system]] itself supports it.

On Unix systems, the execute permission controls access to invoking the file as a program, and applies both to executables and scripts.
As the permission is enforced in the [[Loader (computing)|program loader]], no obligation is needed from the invoking program, nor the invoked program, in enforcing the execute permission{{Snd}} this also goes for shells and other interpreter programs.
The behaviour is mandated by the [[C POSIX library|POSIX C library]] that is used for interfacing with the kernel. POSIX specifies that the <code>exec</code> family of functions shall fail with EACCESS (permission denied) if the file denies execution permission (see {{man|sh|execve|SUS}}).

The ''execute'' permission only applies when the script is run directly. If a script is invoked as an argument to the interpreting shell, it will be executed regardless of whether the user holds the ''execute'' permission for that script.

Although Windows also specifies an ''execute'' permission, none of the Windows-specific shells block script execution if the permission has not been granted.