We can accomplish a self-executing script with a special syntax, #!, called a shebang, or sometimes hash-bang, as the first line of the script. This syntax is treated specially by the kernel, and specifies the program that should be used to run the rest of the script—the interpreter.
We edit hello.bash to put the shebang as the very first line of the script:
#!/bin/bash printf 'Hello, %s!\n' "$USER"
The preceding syntax assumes that your Bash shell is in the common location of /bin/bash. You can find out where yours is by checking the value of the BASH variable:
bash$ declare -p BASH declare -p BASH="/usr/local/bin/bash"
We also need to use the chmod system program to make the script executable:
bash$ chmod +x hello.bash ...
