What does NOEXEC flag mean when mounting directories on RHEL?

I am trying to understand the NOEXEC flag when mounting.

I am having an execution issue within the /tmp directory on someone elses machine that I cannot access atm where the /tmp directory is mounted onto a different drive than '/' and NOEXEC is present. I wanted to try and recreate this scenario on my machine, but I do not have a second hard drive. I tried doing the following command:

mount --bind /test1 /test2

I then removed the bind flag and added NOEXEC in /etc/fstab. Then, I created a file in /test2 called test.sh where it just echos 'hello world'. I try and run it and it said 'permission denied'. I then ran chmod 777 test.sh and was able to execute the file just fine. I thought that the NOEXEC flag should not allow me to execute anything?

Is mount --bind /test1 /test2 not the same as mounting from a completely different physical drive? As in /test1 and /test2 are on different drives?

Solution 1:

Option 'NOEXEC' flag in the mount command does not allow the execution of executable binaries in the mounted file system¹. However, when a script (a text file that begins with she-bang line; i.e., a line that begins with #!) is given to some shells (bash), it will run the executable named on that line (e.g., /usr/bin/perl) and pass the path of the shell script as the first argument. The actual interpreter might not be on that mountpoint.
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¹ The mount command typically mounts a file system.  (Arguably, loop-back or bind mounts may be considered an exception to this generality.)  In some cases (e.g., /tmp), this file system will contain only one directory.