fsevmgr

QNX SDP8.0Utilities ReferenceUtilities

Filesystem event manager

Syntax:

fsevmgr [options]

Runs on:

QNX OS

Options:

-c clients
The maximum number of concurrent clients for the filesystem event manager. Each call to inotify_init() or inotify_init1() creates a new client. This value must be less than or equal to 256. The default is 256.
-s size
The size of each client's event queue in bytes. The suffix k or K can be used to specify this value in kilobytes. The maximum value allowed is 32KB; this is also the default value.
-v
Increase verbosity (i.e., log more information to slogger2). You can specify up to three -v's to log the most information.

Even with no -v's, critical messages will be sent to slogger2.

-w watches
The maximum number of system-wide concurrent watches. The maximum value allowed is 4096; this is also the default value.

Description:

The fsevmgr service forwards filesystem event watch requests from clients to filesystems, and gathers events and sends them to clients that want to be notified of filesystem events.

Note:
  • The fsevmgr process must be started before any filesystem resource manager processes that are expected to provide filesystem event notifications.
  • In this release, fsevmgr doesn't take command strings to execute (it takes just those options explained above) and always runs in the background.
The fsevmgr service registers the following paths in the system namespace:
/dev/fsnotify
Used by the fsnotify library to provide event data, in the form of inotify_event structures, to clients that are listening for filesystem events; for more information, see inotify_init() in the C Library Reference. All application processes that need to use filesystem event watches must have permission to access this file.

The fsevmgr service depends on this library. This means libfsnotify.so must be present in the paths specified by LD_LIBRARY_PATH. For more information about this environment variable, see Setting PATH and LD_LIBRARY_PATH in the QNX OS User's Guide.

/dev/fsmgr
Used by resource managers that will generate filesystem events and send their data to fsevmgr. All filesystem processes that are expected to support filesystem event watches must have permission to read and write this file.
You can make fsevmgr use non-default paths for these interfaces by defining the FSNOTIFY_PREFIX environment variable (see below).

The permissions and ownership of both of these paths are controlled by security policies, using secpol_resmgr_attach(). This allows for centralized configuration of these attributes.

Environment variables:

FSNOTIFY_PREFIX
Prefix to use in the paths registered in the system namespace. Client programs and resource managers also prepend this variable's value to the paths they use for connecting to the fsevmgr service for reading and writing data. If you don't define FSNOTIFY_PREFIX, the default prefix used is /dev, meaning the service registers its interfaces under this path. If you do define the variable, you must set it to the same value for fsevmgr and for any programs that use this service.
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