Linux provides a nice interface for monitoring all file system events like creating, modifying, removing files. The interface is inotify
family of system calls, the userspace utilities leveraging these calls are provided by the inotify-tools
package in Ubuntu (available on the universe repository). If you don't have it already, install by:
sudo apt-get install inotify-tools
inotify-tools
provides inotifywait
and inotifywatch
binaries, we need the first one.
So you want to run the command asciidoctor -q some_file
when any .adoc
file is modified (some_file
will replaced by that), if so assuming your .adoc
files are in directory /foo/bar
, you can set the watch:
inotifywait -qm --event modify --format '%w' /foo/bar/*.adoc
-q
enables the quiet mode, no info from inotifywait
itself
-m
enables monitor mode, otherwise it will exit after the first event
--event modify
, we are only interested in modify
event i.e. when a file is modified. Other possible values include open
, close
etc.
--format %w
, we only want the file name that is modified rather than bunch of other info as we will use the file name as input to another command
/foo/bar/*.adoc
will be expanded to all .adoc
files under /foo/bar
directory
Now the above will show you the filename whenever any is modified, now to run the command on the filename (assuming the command takes arguments via STDIN):
inotifywait -qm --event modify --format '%w' /foo/bar/*.adoc | while read -r file ; do
asciidoctor -q "$file"
done
You can also setup a recursive watch on the directory, you will then need to use grep
to filter the desired files only. Here setting the watch recursively (-r
) on directory /foo/bar
and using grep
to filter only .adoc
files:
inotifywait -qrm --event modify --format '%w%f' /foo/bar | grep '\.adoc$' | while read -r file ; do
asciidoctor -q "$file"
done
When watching directories the output format specifier %w
resolves to the directory name, so we need %f
to get the file name. While watching files, %f
would resolve to empty string.
Note that, you can also run inotifywait
in daemon (-d
) mode, you can also script the whole thing, and/or run in background, and/or play with it more other options.
Also, you can replace asciidoctor
with any other command of your choice, if you want.
Check man inotifywait
to get more idea.