SC2239 – ShellCheck Wiki

Ensure the shebang uses the absolute path to the interpreter.

Problematic code:

#!bin/sh
echo "Hello World"

Correct code:

#!/bin/sh
echo "Hello World"

Rationale:

The script's interpreter, as specified in the shebang, does not start with a /.

The interpreter should always be specified by absolute path to ensure that the script can be executed from any directory. When it's not, it's generally a typo like in the problematic example.

If you don't know where the interpreter is and you hoped to use #! bash, this is not an option. Use /usr/bin/env instead:

#!/usr/bin/env bash
echo "Hello World"

While not required by POSIX, env can essentially always be found in /usr/bin and will search the PATH for the specified executable.

Exceptions:

None.

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