A simple file/directory watcher for Linux built on top of
[inotify] inotify(7).
Here's the result of watching /root while performing ls /root in another
shell, then opening another bash and finally exiting with Ctrl-C:
root@7e3a25bd2ab5:/opt/64091/inotify-watcher# ./watcher /root/
Event descriptions:
Event c: Object was created
Event o: Object was opened
Event r: Object was accessed
Event w: Object was modified
Event <: Object was moved (original name)
Event >: Object was moved (new name)
Event d: Object was deleted
Event x: Object not opened for writing was closed
Event X: Object opened for writing was closed
Waiting for events...
2016-09-21 10:19:06.451041: Event: o (path: /root/, watch: 1, cookie: 0)
2016-09-21 10:19:06.451095: Event: r (path: /root/, watch: 1, cookie: 0)
2016-09-21 10:19:06.451123: Event: r (path: /root/, watch: 1, cookie: 0)
2016-09-21 10:19:06.451146: Event: x (path: /root/, watch: 1, cookie: 0)
2016-09-21 10:19:08.681225: Event: o (path: /root/.bashrc, watch: 1, cookie: 0)
2016-09-21 10:19:08.681282: Event: r (path: /root/.bashrc, watch: 1, cookie: 0)
2016-09-21 10:19:08.681312: Event: x (path: /root/.bashrc, watch: 1, cookie: 0)
2016-09-21 10:19:08.681385: Event: o (path: /root/.bash_history, watch: 1, cookie: 0)
2016-09-21 10:19:08.681415: Event: r (path: /root/.bash_history, watch: 1, cookie: 0)
2016-09-21 10:19:08.681433: Event: x (path: /root/.bash_history, watch: 1, cookie: 0)
2016-09-21 10:19:08.681477: Event: o (path: /root/.bash_history, watch: 1, cookie: 0)
2016-09-21 10:19:08.681500: Event: r (path: /root/.bash_history, watch: 1, cookie: 0)
2016-09-21 10:19:08.681519: Event: x (path: /root/.bash_history, watch: 1, cookie: 0)
^CRun time: 6.406790s
Total events: 13
inotify queue overflows: 0
read() buffer resizes: 1
It can watch as many directories as specified on the command line (although
it's limited by the number of watches available to an inotify instance, and
it's single-threaded to boot, meaning that watching many files/directories may
lead to more lost events).
inotify(7)[] provides background on how the watch mechanism worksinotifywait[] is a similar tool