Waits for write, rename and delete events on files and file creation and deletion events in directories and returns. Please note, that simply touching a file will not trigger a return.
Supports waiting on multiple files and directories. When waiting on a directory, adding a file, or deleting a file will trigger a return. Everything else (like touching or writing) will not trigger a return.
This tool is inspired by inotifywait, the original kqueue paper, and the lack of anything similar (to the best of my knowledge) on Mac OS X.
- Xcode (Command Line Tools suffice)
Waiting on directories does not work on Linux at the moment.
To build this just type:
make
If you want to check that everything is working correctly on your machine use:
make test
This requires perl, with modules IPC::Run and Test::More installed.
Call it like this:
kqwait [-d] [-v] [-h] <file|dir>[ <file|dir>]+
d- enable debug output on stderrv- print version and exith- print help
The tool prints the file or directory that caused the tool to wake up,
and returns 0, if the expected event occured, 1 otherwise.
When waiting on a directory, a + character is prepended if a file was
added, a - if a file was deleted.
Use it in a shell script like this:
while ./kqwait text.txt; do
# do some stuff on write
done
Or watch directories like this:
$ while ./kqwait somedir someotherdir; do true; done
+ somedir/a_file_was_added.txt
- someotherdir/a_file_was_deleted.txt
When watching directories, write events concerning existing files currently won't trigger a return. Only creation and deletion will do that. If you would like to track all events at the same time you can use shell mechanisms to do that:
while ./kqwait dir1/ dir1/*; do
# something
done
If you want to use the file that caused the return, you can assign the output to a variable:
while file=`./kqwait dir1/`; do
echo "Event on $file"
done
See a more advanced script, that does some simple dispatch based on file
ending under samples/.
There is (at least) one race condition in this code, when waiting for changes on directories. If several events happen on a directory in quick succession, this tool might catch an intermediate snapshot of that chain of events.
Sven Schober sv3sch@gmail.com
Copyright (c) 2020, Sven Schober
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