wendy

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                -- by z3bra
===========================

(W)atch (EN)tire (D)irector(Y) is an inotify-based directory watcher.

With wendy, you can watch event in directories or files, and launch a
specific command when an event occurs.

The program is made the more simple possible, to leave the room to unlimited
uses. Be creative !

Every event raised by inotify is handled. Just sum them up to watch multiple
event at the same time. Here is the full table:
(see inotify(1) for a better explanation of those events)

    IN_ACCESS ........ 1
    IN_MODIFY ........ 2
    IN_ATTRIB ........ 4
    IN_CLOSE_WRITE ... 8
    IN_CLOSE_NOWRITE . 16
    IN_OPEN .......... 32
    IN_MOVED_FROM .... 64
    IN_MOVED_TO ...... 128
    IN_CREATE ........ 256
    IN_DELETE ........ 512
    IN_DELETE_SELF ... 1024
    IN_MOVE_SELF ..... 2048

To watch for both creation AND deletion in a directory, do some math:

    256 + 512 = 768

then, pass that value to wendy so that she can watch after both of them (did I
just say 'she'?).

You can also note that you can specify file/directory names either using the
-f flag, or from stdin (in this case, the -f flag must be omited).
As a hidden feature, the watch mask is changed everytime the -m flag is
provided, and the inotify watches are set everytime the -f flag is given. So
you can wathc different mask on different file using the same command, and
that's pretty cool!

Here are some examples:

    # Tell me whenever I have a new mail
    wendy -m 256 -d ~/mails/INBOX/new -t 60 -e espeak "You got a new mail"

    # On-the-fly recompilation
    wendy -l | grep -i close_write
    IN_CLOSE_WRITE ... 8
    find -name "*.c" | wendy -m 8 -q -d ~/src/dev/program/ -t 1 -e make


    # Get up to date with community based projects
    wendy -m 770 -f /mnt/nfs/project/ -t 30 -e popup 'project updated'

    # watch creation in the directory, and modifications on a file
    wendy -m 256 -f ./my_dir -m 8 -f file.txt -e echo awesome!

FAQ
===

> Can it work on a folder and sub folders ?

It does not. inotify does not handle this by default, and implementing this
would make the code grow in complexity to a level I don't want to reach.
But you could do something like:

    $ tree
    .
    ├── a
    ├── b
    │   ├── c
    │   └── d
    └── e

    5 directories, 0 files

    $ find a -type d | wendy -m 256 -v | cut -f2

That will add a watch to each directory, and output the names of the file
created (eg: "a/b/newfile").

---

> Can you explain why this exists? Doesn't inotifywait (from inotify-tools) do
> this exact same thing?

When I first started wendy, I was not aware of inotifywait. It was just a good
programming exercise.

With the time, I found wendy more and more useful, and added a few options to
make it faster and more 'generic' (It was first created to watch my mail
directory, to alert me of new mails).

Today, I know that inotifywait can be used for everything wendy does Anyway, I
still prefer using wendy because of this:

    * inotifywait exits upon event reception [1]
    * inotifywait does not allow to launch a command on event reception [2]
    * inotifywait with multiple events can end in an infinite line [3]
    * inotifywait cna't read names from stdin
    * inotifywait only handle the file modification event (eg, wendy can use
      the IN_ONLYDIR mask)
    * inotifywait exits right when an event occur, wendy can treat all queued
      events at a specific period
    * inotify-tools : 164kb against 12kb for wendy (ok, not that relevant)
    * I like the name 'wendy' better

[1] I'm aware of the '--monitor' flag, but the only way to exec a command with
this is a pain that implies read, a while loop and so on.

[2] In fact, you can, by doing "inotifywait -e <event> && command", and
wrapping it in a while loop. Well, don't forget to add a test to see if your
file still exists, to avoid infinite buggy loops. You'll end up with something
like:

    while test -e ~/path/to/my/file; do
        inotifywait -e <event> ~/path/to/my/file && command
    done

Good luck with this, I prefer "wendy -m <mask> -e command"

[3] one flag per event. events written in words:

    inotifywait -e access -e create -e delete -e modify -e attrib /path/to/file

I prefer

        wendy -m 774 -f ~/path/to/my/file

---

> Would you prefer to fight one horse sized duck, or 10 duck sized horses ?

Regarding size and number, I'd rather fight horses. Ducks are silly creatures.