Change the #! line (shebang) occurring in Python scripts. The new interpreter pathname must be given with a -i option.
Command line arguments are files or directories to be processed. Directories are searched recursively for files whose name looks like a python module. Symbolic links are always ignored (except as explicit directory arguments).
The original file is kept as a back-up (with a "~" attached to its name), -n flag can be used to disable this.
Sometimes you may find shebangs with flags such as #! /usr/bin/env python -si.
Normally, pathfix overwrites the entire line, including the flags.
To change interpreter and keep flags from the original shebang line, use -k.
If you want to keep flags and add to them one single literal flag, use option -a.
Undoubtedly you can do this using find and sed or perl, but this is a nice example of Python code that recurses down a directory tree and uses regular expressions. Also note several subtleties like preserving the file's mode and avoiding to even write a temp file when no changes are needed for a file.
In Fedora Linux, this tools is a part of python-rpm-macros RPM package in /usr/lib/rpm directory.
This tool has been in CPython since version 2.0 (August 1994) until October 2022 and version 3.12.
Because we (Python maintenance team in Red Hat) use this tool in Fedora Linux to fix shebangs in RPM packages we decided to create a new upstream for it and allow other users to use it and contribute to it.