Bash script Error /bin/bash^M: bad interpreter: No such file or directory

Have you ever been slapped with the /bin/bash^M: bad interpreter: No such file or directory error when trying to run a bash script, be it from cron or command line?

If your answer is yes then you have reached the right place. This error is more common than you think and is quite harmless but nevertheless, it is annoying.

This issue is caused when you create scripts in Windows environments and then port them over to run on a Unix environment.

Unix uses different line endings therefore it can’t properly read the file you created on Windows. Bash scripts on the other hand are quite sensitive to line-endings. This is not just limited to the script itself. it extends to the data that the script processes.

With that in mind, it is important that one should have Unix-style line-endings, i.e., each line is terminated with a Line Feed character \n which is (decimal 10, hex 0A in ASCII).

With Windows or DOS-style line endings, each line is terminated with a Carriage Return followed by a Line Feed character \r\n.

The Bash script sees the Carriage Return \r as ^M. In this case, the Carriage Return (^M or \r) is not treated as whitespace. and is appended to the line as text wherever it appears at line endings. So this:

!/bin/bash

becomes:

!/bin/bash^M

Since there is no interpreter, command, directory, or file called bash^M we get the bad interpreter: No such file or directory error.

Solution to Fixing /bin/bash^M: bad interpreter: No such file or directory

There are several options one may have to solve this problem. Since we know ^M is an illegal character the simple solution is to get rid of it. We will just show you two simple ways to do it.

1. This can be done using the dos2unix program to convert the Carriage Return characters:

$ dos2unix filename

You can download the dos2unix program from this location.

2. Correct the problem from the source. That is whichever editor (Sublime, Notepad++, VS Code, etc) you use in Windows you should be able to change the settings to use the Unix style line endings.

For example in Notepad++ in the bottom right of the screen, you will be able to see the document format. By default, it will say Windows (CR LF). To change it either:

• Go to Settings > Preferences
• Select New Document
• In the Format (Line ending) section select Unix (LF)
• Click the Close button to save preferences

or

• Right-click on the Windows (CR LF) label on the bottom right of the screen to trigger the context menu.
• Select Unix LF

Each editor has their personalized ways of changing the Line ending format which should be shown in the bottom right corner of the editor window. Usually Left or right-clicking the label should display the options you have.

Conclusion

There you have it. You should be able to understand why and get rid of the /bin/bash^M: bad interpreter: No such file or directory bash script error from all your scripts and data they act upon.

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