The #! (shebang) is a special line at the beginning of a shell script that tells the operating system which interpreter to use to execute the script. The shebang line consists of a pound sign (#) and an exclamation point (!) followed by the path to the interpreter executable. For example, the shebang line for a bash script might look like this:  #!/bin/bash  The shebang line is not required for all shell scripts, but it is a good practice to include it so that the script can be run directly from the command line without having to specify the interpreter. For example, if we include the shebang line in a script and make the script executable (using chmod +x script.sh), we can run the script simply by typing ./script.sh instead of bash script.sh.  Without a shebang line, the operating system will not know which interpreter to use to execute the script, and the script will not be able to run.