The origin of the shebang

Today, 42 years ago, on the 10th of January, Dennis Ritchie – the co-creator of C and Unix – wrote the following:

From dmr Thu Jan 10 04:25:49 1980 remote from research

The system has been changed so that if a file being executed begins with the magic characters #! , the rest of the line is understood to be the name of an interpreter for the executed file.

~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~

To take advantage of this wonderful opportunity,
put

#! /bin/sh
 
at the left margin of the first line of your shell scripts.

Wikipedia has an article about the shebang and mentions the following: “Dennis Ritchie (DMR) introduced kernel support for interpreter directives in January 1980”. Maybe “interpreter directive” sounds cool, but you can’t deny that “shebang” has more sex appeal.

The purpose of the Shebang

A shebang is a special directive in a script or program. It’s the first line of code and tells the shell which interpreter to use for execution.

#! /bin/sh

In other words, it instructs the system as follows: “run this script with this specific application.” It depends on the script and the programming language which application to use — the Python interpreter for Python scripts, the Bash command for Bash scripts, and so on.

The etymology

Most of us will know the # character as the hashtag. But it’s also called a pound sign when combined with numbers. Or the sharp when used in musical notation (or in the C# programming language). However, less known is that a bang is another word for the exclamation mark. Let’s put these two together, and the shebang is born.

<Fred> 🙋🏼‍♂️: Just a thought: Shellbang, as in, execute with the following shell?

Hello World

Today we also celebrate another birthday. The birth of Kaboom Shebang, the blog of Kaboom, named after Kaboom’s mascot: the shebang. In the first publication, we’ll set a challenge for this blog. Read more about that challenge in the /born-by-smart-contract article.

So in the style of that program we programmers wrote at least once, but perhaps many times: Hello World!.