fsevmgr

Note:

The random daemon must be running before you start fsevmgr.

Syntax:

fsevmgr [options] [command]

Runs on:

QNX OS

Options:

-d

Enable debugging output on stdout.

-F group id

The group ID or name for the fsnotify device; see below.

-f fsnotify_name

The name for fsnotify to register (default: /dev/fsnotify).

CAUTION:

Don't change the name of /dev/fsnotify; doing so will break the inotify system.

-k size

The size of each mailbox event queue, in kilobytes (default: 64 KB).

-m

Allow multiple events to be returned per read(). This is enabled for all inotify-style watches.

-s size

The size of the master event queue, in kilobytes (default: 100 KB).

-U uid:gid

Switch to the given user ID and group ID once running.

-w time

The number of milliseconds to delay before notifying io-blk instances.

-y

Suppress the notification of the event manager load.

command

A specific command to execute; one of the following:

-c id, string: Insert an event into the event manager queue.
-D value: Set the debugging level.
-j: Display statistics.
-M muid: Report the status of the given mailbox.
-P path: Poll the event manager and display the output on the given path.
-p: Poll the event manager and display the output on standard output.
-r: Display the primary event queue on standard output.
-S: Report the event manager's status.
-u: Notify filesystems to resynchronize themselves with the event manager.

Description:

The fsevmgr manager gathers events from the block I/O (io-blk.so) system and sends them to clients that want to be notified of changes to a filesystem. It uses mailboxes to manage event queues, creating one mailbox to serve as the master event queue, and then creating a mailbox for each open() request from a client.

If you specify a command argument, then fsevmgr completes the requested operation and exits immediately. If you don't specify a command, fsevmgr runs in the background.

By default, fsevmgr registers these interfaces in the system namespace:

/dev/fsnotify: Used by the inode notify system as a source of inotify_event structures; see inotify_init() in the C Library Reference.

The devb-* driver needs to be able to locate these names, and needs write access to them. The fsevmgr advertises itself to devb-* on starting unless you specify the -y option. If the devb-* driver isn't running as root (that is, you specified a user ID and a group ID on its command line), the group ID for the fsnotify devices must match the primary or supplementary group ID given to devb-*. For example, the following commands start devb-ahci as uid 121 and gid 132, and give it access to the fsnotify entries:

fsevmgr -F 132
devb-ahci cam user=121:132

The fsevmgr manager uses the following custom abilities, which are given to root users by default:

fsevmgr/qnxext (INOTIFY_ABILITY_QNX_EXT) — Check for processes that want to listen to any of the QNX extended inotify events.
fsevmgr/recurse (INOTIFY_ABILITY_RECURSE) — Reserved for future use.