Re: Factor

Factor: the language, the theory, and the practice.

File Monitor

Tuesday, May 5, 2015


Factor has a cross-platform file-system change monitor which supports detecting changes to file names, attributes and contents under a specified directory.

There is some minor platform differences between Mac OS, Windows, and Linux which may be worth looking at if you are building on top of the io.monitors vocabulary. I was curious about what kind of events are generated for various test-cases and built a small utility to experiment with it.

Some code to monitor for changed paths recursively in a directory and print each one out:

: watch-loop ( monitor -- )
    dup next-change path>> print flush watch-loop ;

: watch-directory ( path -- )
    [ t [ watch-loop ] with-monitor ] with-monitors ;

I’ve committed this as the file-monitor tool (with support for an optional command-line argument to specify which directory to monitor as well as printing the change descriptors). You can run it very simply:

$ factor -run=file-monitor [path]

An example session on Linux, monitoring some simple changes to files in /tmp:

$ factor -run=file-monitor /tmp &
Monitoring /tmp

$ touch /tmp/a
{ +add-file+ } /tmp/a
{ +add-file+ } /tmp/a
{ +modify-file+ } /tmp/a

$ echo "test" > /tmp/a
{ +modify-file+ } /tmp/a

$ rm /tmp/a
{ +remove-file+ } /tmp/a