Capture filesystem changes using overlayfs.
jan runs a command in a chroot, capturing all filesystem changes it makes using overlayfs, and saves the resulting files in an isolated directory tree. It does not use LD_PRELOAD, so it works even with statically-linked programs, though it does require root privileges.
jan depends on coreutils, mountpoint (part of util-linux), and a POSIX-compliant shell. Linux 3.18 or greater is also required.
Install from a Debian package, or run make install from a
release tarball or development sources.
$ jan PATH COMMAND...
where PATH is the directory in which jan should store the files
created by COMMAND, which will be run as root.
Note that jan will not create PATH if it doesn't already exist, in
order to avoid inadvertently leaving you with a directory owned by root.
In addition, it must be possible for jan to create a temporary directory
next to PATH (not beneath), and that temporary directory must be on
the same filesystem as PATH, which in practice means that jan cannot
operate if a filesystem is mounted at PATH (it will attempt to tell
you if this is the case).
See the overlayfs documentation for detailed information on how jan deals with e.g. file deletions.
Contributions are welcome!
Everyone interacting with this project is expected to abide by the terms of the Contributor Covenant Code of Conduct. Violations should be reported to coc-enforcement-jan@sorrel.sh.
Copyright © 2020 Ash Holland. Licensed under the EUPL (1.2 or later).
