Shebang in Bash Script

  1. Bash Shebang (#!) and How to Use It
  2. Make Linux Scripts Portable

This tutorial explains what the shebang is and its usage in bash scripts.

Bash Shebang (#!) and How to Use It

The #! syntax is used in shell scripts to indicate the interpreter to execute the script in Unix/Linux operating systems.

#!/bin/bash

The shebang starts with the # sign and an exclamation mark followed by the full path to the interpreter.

In the case of the code snippet given above, it specifies that the script should be executed using bash as the interpreter, and the bash interpreter can be found in the /bin directory. We assume that bash has been installed in the /bin directory.

Scripts in Linux are executed by the interpreter specified on the first line.

Let us write a script that uses #!/bin/bash. The script below prints all the content of the folder in a long format using bash as its interpreter.

#!/bin/bash

ls -al

Make Linux Scripts Portable

#!/bin/bash assumes that bash is installed in the /bin directory. However, this is not always the case across different Unix like operating systems. To make scripts more portable, use #!/usr/bin/env bash.

#!/usr/bin/env bash

This tells the shell to search for the first match of bash in the $PATH variable and use the first one it finds as the interpreter. This is useful if you are not aware of the absolute path of the interpreter on the system.

Let us write a script that uses #!/usr/bin/env bash. The script below prints all the folder’s content in a long format using the first bash shell it finds in the $PATH variable as its interpreter.

#!/usr/bin/env bash

ls -al
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