<2>fam<1> is a server that tracks changes to the filesystem and
relays these changes to interested applications.
Applications such as
<2>fm<1>(1G) and mailbox(1) present an up-to-date view of the filesystem.
In the absence of <2>fam<1>, these applications and others like them
are forced to poll the filesystem to detect changes.
<2>fam<1> is
more efficient.
Applications can request <2>fam<1> to monitor any files or directories in
any filesystem.
When <2>fam<1> detects changes to monitored files, it notifies
the appropriate application.
The FAM API provides a programmatic interface to <2>fam<1>; see
fam (3X). <2>fam<1> is informed of filesystem changes as they happen by the
kernel through the <2>imon<1>(7M) pseudo device driver.
If asked to
monitor files on an NFS mounted filesystem, <2>fam<1> tries to use
<2>fam<1> on the NFS server to monitor files.
If <2>fam<1> cannot
contact a remote <2>fam<1>, it polls the files instead.
<2>fam<1> also polls special files.
Normally, <2>fam<1> is started by <2>inetd<1>(1M).
It is registered with
<2>portmap<1>(1M) as performing the sgi_fam service.
OPTIONS
<3>-l<1>
Disable polling of NFS
files.
It does not disable use of remote <2>fam<1> on NFS servers,
nor does it disable polling of local files.
<3>-t<1> <2>NFS_polling_interval<1>
Set the interval for polling files to <2>NFS_polling_interval<1> seconds.
The default
is six seconds.
<3>-T<1> <2>idle_timeout<1>
Set the idle timeout interval to <2>idle_timeout<1>.
fam exits <2>idle_timeout<1> seconds after its
last client disconnects.
A value of 0 causes fam to wait indefinitely for new connections.
The default is five seconds.
<3>-f<1>
Remain in the foreground instead of spawning a child and exiting.
This option is ignored if <2>fam<1> is started by <2>inetd<1>.
<3>-v<1>
Turn on verbose messages.
<3>-d<1>
Enable verbose messages and debug messages.
<3>-p<1> <2>program<3>.<2>version<1>
Use the specified RPC program and version numbers.
<3>-L<1>
Local-only mode. <2>fam<1> will only accept requests from clients running on the
local machine. This overrides the <2>local_only<1> flag in the configuration
file. This option is ignored if <2>fam<1> is started by <2>inetd<1>.
<3>-C<1>
Compatibility mode. This disables authentication and reduces access security
as described under SECURITY below. This overrides the
<2>insecure_compatibility<1> flag in the configuration file.
<3>-c<1> <2>config_file<1>
Read configuration information from the given file rather than the default,
which is <2>/etc/fam.conf<1>.
CONFIGURATION FILE
In addition to its command-line options, <2>fam<1>'s behavior can also be
controlled through its configuration file. By default, this is
<2>/etc/fam.conf<1>; the <3>-c<1> command-line option can be used to specify
an alternate file. Configuration lines are in the format <2>option=value<1>.
Lines beginning with <2>#<1> or <2>!<1> are ignored.
<2>fam<1> recognizes the following options:
<3>insecure_compatibility<1>
If set to <2>true<1>, this disables authentication and reduces access security
as described under SECURITY below. This is <2>false<1> by default. Setting
this option to <2>true<1> is the same as using the <3>-C<1> command-line
option.
<3>untrusted_user<1>
This is the user name or UID of the user account which <2>fam<1> will use for
unauthenticated clients. If a file can't be <2>stat<1>'ed by this user,
<2>fam<1> will not tell unauthenticated clients about the file's existence.
If an untrusted user is not given in the configuration file, <2>fam<1> will
write an error message to the system log and terminate.
<3>local_only<1>
If set to <2>true<1>, <2>fam<1> will ignore requests from remote <2>fam<1>s.
This is <2>false<1> by default. Setting this option to <2>true<1> is the same
as using the <3>-L<1> command-line option. This option is ignored if
<2>fam<1> is started by <2>inetd<1>.
<3>xtab_verification<1>
If set to <2>true<1>, <2>fam<1> will check the list of exported filesystems
when remote requests are received to verify that the requests fall on
filesystems which are exported to the requesting hosts. This is
<2>true<1> by default. If this option is set to <2>false<1>, <2>fam<1> will
service remote requests without attempting to perform the verification. If
the <2>local_only<1> configuration option or <3>-L<1> command-line option is
used, <2>xtab_verification<1> has no effect.
SECURITY
For backward compatibility, the <3>-C<1> command-line option and
<2>insecure_compatibility<1> configuration option can be used to disable
authentication. Configuring <2>fam<1> this way opens a publically known
security weakness whereby a "rogue client" can obtain the names of all the
files and directories on the system.
<2>Note that fam never opens the files it's monitoring<1>, and cannot
be used by a rogue client to read the contents of any file on the system.
<2>fam<1> only gives out the names of monitored files, and only monitors files
which the client can
stat (1M). Users can stat a file without having read permission on it as long as
they have search permission on the directory containing it.
