Use env in the Shebang/Hashbang Line

Pre-Requisite

Understand: What is hashbang/shebang...

From Shebang Hashbang

What is a Shebang?

A shebang (also called a "hashbang") is a special sequence of characters at the beginning of a script file that tells the system which interpreter to use to execute the script.

Syntax

The shebang always starts with #! followed by the path to the interpreter:

#!/path/to/interpreter

How it works

When you run a script directly (like ./myscript.sh), the operating system reads the first line. If it starts with #!, the system uses the specified interpreter to run the script instead of trying to execute it as a binary.

Common examples

#!/bin/bash          # Bash script
#!/usr/bin/python3   # Python script  
#!/usr/bin/env node  # Node.js script
#!/usr/bin/env ruby  # Ruby script

Why use it?

Without a shebang, you'd need to manually specify the interpreter every time:

# Without shebang
bash myscript.sh

# With shebang
./myscript.sh

The shebang makes scripts self-executing and portable across different systems.

Content

The env command is used to find and run the bash interpreter according to the user's environment.

This is particularly useful when running on macOS, which comes with an outdated bash version 3 in /bin/bash. Using #!/usr/bin/env bash instead of #!/bin/bash allows the OS to find the interpreter on the system path rather than being hard coded to /bin/bash version of interpreter that comes with OS.

In Short

✅ Do this:

#!/usr/bin/env bash

❌ Don't do this:

#!/bin/bash

For Searchability

Bash She bang; Bang character vb