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Shebang Line: The First Line

The shebang line tells the system which interpreter to use.

Here's the thing: The shebang is the first line. It's important. Use it.

What It Is​

#!/bin/bash

The #!: That's the shebang. Tells the system what to use.

My take: Shebang is simple. But important. Always use it.

Common Shebangs​

bash​

#!/bin/bash

My take: Use this for bash scripts. Most common.

sh​

#!/bin/sh

My take: Use this for sh scripts. When you need portability.

Find in PATH​

#!/usr/bin/env bash

My take: This finds bash in PATH. More portable. Use it.

Why It Matters​

Without shebang, you need to run:

bash script.sh

With shebang, you can run:

./script.sh

My take: Shebang makes scripts executable. Use it.

Common Patterns​

Standard bash​

#!/bin/bash

Portable bash​

#!/usr/bin/env bash

Common Mistakes (I've Made These)​

  1. Forgetting shebang: Always include shebang. First line.

  2. Wrong path: Use /bin/bash or /usr/bin/env bash. Check your system.

  3. Spaces: No spaces after #!. It breaks.

  4. Wrong interpreter: Make sure you use the right one. bash for bash scripts.

What's Next?​

Now that you understand shebang, let's talk about Making Scripts Executable.

Personal note: I used to forget shebang. Then scripts wouldn't run. Now I always include it. First line. Always.