Whatfiles – Log What Files Are Accessed By Any Linux Process

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Whatfiles is a Linux utility that logs what files another program reads/writes/creates/deletes on your system. It traces any new processes and threads that are created by the targeted process as well.

Rationale:

I’ve long been frustrated at the lack of a simple utility to see which files a process touches from main() to exit. Whether you don’t trust a software vendor or are concerned about malware, it’s important to be able to know what a program or installer does to your system. lsof only observes a moment in time and strace is large and somewhat complicated.

Sample output:

mode:  read, file: /home/theron/.gimp-2.8/tool-options/gimp-clone-tool, syscall: openat(), PID: 8566, process: gimp
mode: read, file: /home/theron/.gimp-2.8/tool-options/gimp-heal-tool, syscall: openat(), PID: 8566, process: gimp
mode: read, file: /home/theron/.gimp-2.8/tool-options/gimp-perspective-clone-tool, syscall: openat(), PID: 8566, process: gimp
mode: read, file: /home/theron/.gimp-2.8/tool-options/gimp-convolve-tool, syscall: openat(), PID: 8566, process: gimp
mode: read, file: /home/theron/.gimp-2.8/tool-options/gimp-smudge-tool, syscall: openat(), PID: 8566, process: gimp
mode: read, file: /home/theron/.gimp-2.8/tool-options/gimp-dodge-burn-tool, syscall: openat(), PID: 8566, process: gimp
mode: read, file: /home/theron/.gimp-2.8/tool-options/gimp-desaturate-tool, syscall: openat(), PID: 8566, process: gim p
mode: read, file: /home/theron/.gimp-2.8/plug-ins, syscall: openat(), PID: 8566, process: gimp
mode: read, file: /usr/lib/gimp/2.0/plug-ins, syscall: openat(), PID: 8566, process: gimp
mode: read, file: /home/theron/.gimp-2.8/pluginrc, syscall: openat(), PID: 8566, process: gimp
mode: read, file: /usr/share/locale/en_US/LC_MESSAGES/gimp20-std-plug-ins.mo, syscall: openat(), PID: 8566, process: gimp
mode: read, file: /usr/lib/gimp/2.0/plug-ins/script-fu, syscall: openat(), PID: 8566, process: gimp
mode: read, file: /etc/ld.so.cache, syscall: openat(), PID: 8574, process: /usr/lib/gimp/2.0/plug-ins/script-fu
mode: read, file: /etc/ld.so.cache, syscall: openat(), PID: 8574, process: /usr/lib/gimp/2.0/plug-ins/script-fu
mode: read, file: /usr/lib/libgimpui-2.0.so.0, syscall: openat(), PID: 8574, process: /usr/lib/gimp/2.0/plug-ins/script-fu
mode: read, file: /usr/lib/libgimpwidgets-2.0.so.0, syscall: openat(), PID: 8574, process: /usr/lib/g imp/2.0/plug-ins/script-fu
mode: read, file: /usr/lib/libgimpwidgets-2.0.so.0, syscall: openat(), PID: 8574, process: /usr/lib/gimp/2.0/plug-ins/script-fu
mode: read, file: /usr/lib/libgimp-2.0.so.0, syscall: openat(), PID: 8574, process: /usr/lib/gimp/2.0/plug-ins/script-fu
mode: read, file: /usr/lib/libgimpcolor-2.0.so.0, syscall: openat(), PID: 8574, process: /usr/lib/gimp/2.0/plug-ins/script-fu

Use:

  • basic use, launches ls and writes output to a log file in the current directory:

    $ whatfiles ls -lah ~/Documents

  • specify output file location with -o:

    $ whatfiles -o MyLogFile cd ..

  • include debug output, print to stdout rather than log file:

    $ whatfiles -d -s apt install zoom

  • attach to currently running process (requires root privileges):

    $ sudo whatfiles -p 1234

Distribution

Ready-to-use binaries are on the releases page! Someone also kindly added it to the Arch repository, and letompouce set up a GitLab pipeline as well.

Compilation (requires gcc and make):

$ cd whatfiles
$ make
$ sudo make install

Supports x86, x86_64, ARM32, and ARM64 architectures.

Questions that could be asked at some point:

  • Isn’t this just a reimplementation of strace -fe trace=creat,open,openat,unlink,unlinkat ./program?

    Yes. Though it aims to be simpler and more user friendly.

  • Are there Mac and Windows versions?

    No. Tracing syscalls on Mac requires task_for_pid(), which requires code signing, which I can’t get to work, and anyway I have no interest in paying Apple $100/year to write free software. dtruss on Mac can be used to follow a single process and its children, though the -t flag seems to only accept a single syscall to filter on. fs_usage does something similar though I’m not sure if it follows child processes/threads. Process Monitor for Windows is pretty great.

Known issues:

  • Tabs crash when whatfiles is used to launch Firefox. (Attaching with -p [PID] once it’s running works fine, as does using whatfiles to launch a second Firefox window if one’s already open.)

Planned features:

  • None currently, open to requests and PRs.

Thank you for your interest, and please also check out Cloaker, Nestur, and Flying Carpet!

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