Bash Shebang for dummies?

If a script /path/to/foo begins with #!/bin/bash, then executing /path/to/foo arg1 arg2 is equivalent to executing /bin/bash /path/too/foo arg1 arg2. If the shebang line is #!/bin/bash -ex, it is equivalent to executing /bin/bash -ex /path/too/foo arg1 arg2. This feature is managed by the kernel.

Note that you can portably have only one argument on the shebang line: some unices (such as Linux) only accept one argument, so that #!/bin/bash -e -x would lead to bash receiving the single five-character argument -e -x (a syntax error) rather than two arguments -e and -x.

For the Bourne shell sh and derived shells such as POSIX sh, bash, ksh, and zsh:

• -e means that if any command fails (which it indicates by returning a nonzero status), the script will terminate immediately.
• -x causes the shell to print an execution trace.

Other programs may understand these options but with different meanings.

They are options passed to bash see help set for more info, in this case:

-x  Print commands and their arguments as they are executed.
-e  Exit immediately if a command exits with a non-zero status.