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FAM(3X)								       FAM(3X)

NAME
     fam - File Alteration Monitor (FAM) library routines

SYNOPSIS
     #include <fam.h>

     extern int FAMOpen(FAMConnection* fc);

     extern int FAMClose(FAMConnection* fc);

     extern int FAMMonitorDirectory(FAMConnection *fc,
				    char *filename,
				    FAMRequest* fr,
				    void* userData);

     extern int FAMMonitorFile(FAMConnection *fc,
			       char *filename,
			       FAMRequest* fr,
			       void* userData);

     int FAMSuspendMonitor(FAMConnection *fc, FAMRequest *fr);

     int FAMResumeMonitor(FAMConnection *fc, FAMRequest *fr);

     int FAMCancelMonitor(FAMConnection *fc, FAMRequest *fr);

     int FAMNextEvent(FAMConnection *fc, FAMEvent *fe);

     int FAMPending(FAMConnection* fc);

     typedef struct {
	 int fd;
     } FAMConnection;

     #define FAMCONNECTION_GETFD(fc)	  (fc->fd)

     typedef struct {
	 int reqnum;
     } FAMRequest;

     enum FAMCodes { FAMChanged=1, FAMDeleted=2, FAMStartExecuting=3,
	 FAMStopExecuting=4, FAMCreated=5, FAMMoved=6, FAMAcknowledge=7,
	 FAMExists=8, FAMEndExist=9 };

     typedef struct {
	 FAMConnection* fc;
	 FAMRequest fr;
	 char hostname[MAXHOSTNAMELEN];
	 char filename[NAME_MAX];
	 void *userdata;
	 FAMCodes code;
     } FAMEvent;

									Page 1

FAM(3X)								       FAM(3X)

     extern int FAMErrno;

     extern char *FamErrlist[];

DESCRIPTION
     FAM monitors files and directories, notifying interested applications of
     changes.  Routines for communicating with the fam(1M) server process are
     found in ``libfam.a'', which is loaded if the option ``-lfam'' is used
     with cc(1) or ld(1).  The library ``libC.a'' (``-lC'') must also be
     specified.

     An application calls routines described here to establish a list of files
     for fam to monitor.  Fam generates events on a socket to communicate with
     the application.  The fam process is started when the first connection
     from any application to it is opened.  It exits after all connections to
     it have been closed.

USING FAM
     Here are the steps required to use FAM in an application:

     1.	  Create a connection to fam by calling FAMOpen.  This routine will
	  pass back a FAMConnection structure used in all fam procedures.

     2.	  Tell fam which files and directories to monitor by calling
	  FAMMonitorFile and FAMMonitorDirectory to express interest in files
	  and directories, respectively.

     3.	  Select on the fam socket file descriptor and call FAMPending when
	  the fam socket is active, and FAMNextEvent when FAMPending indicates
	  that an event is available.  Alternatively, call FAMPending (or
	  FAMNextEvent) periodically to check the socket connection to fam to
	  see if any new information has arrived.  If there are no events
	  pending, FAMNextEvent blocks until an event occurs.

     4.	  When the application is through monitoring a file or directory, it
	  should call FAMCancelMonitor.	 If the application wants to
	  temporarily suspend monitoring of a file or directory, it may call
	  FAMSuspendMonitor.  When the application is ready to start
	  monitoring again, it calls FAMResumeMonitor.

     5.	  Before the application exits, it should call FAMClose to free
	  resources associated with files still being monitored and to close
	  the connection to fam.

DATA STRUCTURES
     The FAMConnection Structure

     The FAMConnection data structure is created when opening a connection to
     FAM.  Subsequently it is passed into all FAM procedures.  This structure
     has all the information in it to communicate to fam.

									Page 2

FAM(3X)								       FAM(3X)

     Use the macro FAMCONNECTION_GETFD to access the file descriptor inside
     the FAMConnection, rather than accessing it directly.

     The FAMRequest Structure

     When fam is called on to monitor a file, it passes back a FAMRequest
     structure.	 This structure uniquely identifies the request so that it may
     be cancelled, using FAMCancelMonitor or suspended, using
     FAMSuspendMonitor.

     The FAMEvent Structure

     Changes to files and directories are encoded in the FAMEvent structure.
     The code field of this structure contains one of the following
     enumeration constants:

     FAMChanged
	      Some value which can be obtained with fstat(1) changed for a
	      file or directory being monitored.

     FAMDeleted
	      A file or directory being monitored was deleted or its name was
	      changed.	This event is also generated when monitoring starts on
	      a nonexistent file or directory.

     FAMStartExecuting
	      An executable file or shared library being monitored started
	      executing.  If multiple processes execute the same file, this
	      event only occurs when the first process starts.

     FAMStopExecuting
	      An executable file being monitored which was running finished.
	      If multiple processes from an executable are running, this event
	      is only generated when the last one finishes.

     FAMCreated
	      A file was created in a directory being monitored.  Note: this
	      event is only generated for files created directly in a
	      directory being monitored; subdirectories are not automatically
	      monitored.

     FAMMoved FAMMoved events never occur.  The name remains defined so that
	      programs that reference it will still compile.

     FAMAcknowledge
	      After a FAMCancelMonitor, fam generates a FAMAcknowledge event.
	      Also, if an invalid pathname is specified, fam  generates a
	      FAMAcknowledge event.

     FAMExists
	      When the application requests a file be monitored, fam generates
	      a FAMExists event for that file.	When the application requests

									Page 3

FAM(3X)								       FAM(3X)

	      a directory be monitored, fam generates a FAMExists event for
	      that directory and every file directly contained in that
	      directory.

     FAMEndExist
	      When the application requests a file directory be monitored, a
	      series of FAMExists events is generated as described above.
	      After the last FAMExists message, fam generates a FAMEndExist
	      message.

     If a FAM event applies to a file or directory being monitored, the
     FAMEvent's filename field contains the full pathname that was passed to
     fam.  If an event applies to an entry in a monitored directory, the
     filename field contains the relative path only.  For example, if the
     directory /usr/tmp/xyzzy were monitored, and the file
     /usr/tmp/xyzzy/plugh  were deleted, a FAMDeleted event would be generated
     containing "plugh" in filename.  If the directory itself were deleted,
     filename would contain "/usr/tmp/xyzzy".

PROCEDURES
     FAMOpen, FAMClose

     The application opens a connection to fam by calling FAMOpen.  FAMOpen
     initializes the FAMConnection structure passed in to it and returns 0 if
     successful, otherwise -1.	The variable char* appName should be set to
     the name of your application. The FAMConnection structure is passed to
     all subsequent FAM procedure calls.

     FAMClose frees resources associated with files still being monitored and
     closes a fam connection.  It returns 0 if successful and -1 otherwise.

     FAMMonitorDirectory, FAMMonitorFile

     FAMMonitorDirectory and FAMMonitorFile tell FAM to start monitoring a
     directory or file, respectively.  The parameters to this function are a
     FAMConnection (initialized by FAMOpen), a FAMRequest structure, a
     filename and a user data pointer.	The FAMRequest structure is modified
     to subsequently identify this request.  When the file or directory
     changes, a FAM event structure will be generated.	The application can
     retrieve this structure by calling FAMNextEvent (see description under
     FAMNextEvent).

     FAMMonitorDirectory monitors changes that happens to the contents of the
     directory (as well as the directory file itself); FAMMonitorFile monitors
     only what happens to a particular file.  Both routines return 0 if
     successful and -1 otherwise.

     The filename argument must be a full pathname.

     FAMSuspendMonitor, FAMResumeMonitor

									Page 4

FAM(3X)								       FAM(3X)

     FAMSuspendMonitor temporarily suspends monitoring of files or
     directories.  This is useful when an application is not displaying
     information about files, when it is iconified, for example.
     FAMResumeMonitor signals fam to start monitoring the file or directory
     again.  Changes which occur while monitoring is suspended are enqueued
     and delivered when monitoring is resumed.

     Both of these routines take a FAMConnection and a FAMRequest structure.
     The FAMRequest Structure is returned from the FAMMonitorFile or
     FAMMonitorDirectory routines and return 0 if successful and -1 otherwise.

     Because fam runs as an asynchronous process, FAMNextEvent may return a
     few events regarding a given request after that request has been
     suspended.

     FAMCancelMonitor

     When an application is through monitoring a file or directory, it should
     call FAMCancelMonitor.  This routine will signal fam not to monitor this
     directory anymore.	 The FAMRequest structure is returned from the
     FAMMonitorFile or FAMMonitorDirectory routines.  FAMCancelMonitor returns
     0 if successful and -1 otherwise.

     FAMPending, FAMNextEvent

     FAMPending returns 1 if an event is waiting and 0 if no event is waiting.
     It also returns 1 if an error has been encountered.  This routine returns
     immediately to the caller.

     FAMNextEvent will get the next FAM event.	If there are no FAM events
     waiting, then the calling application blocks until a FAM event is
     received.	If blocking is not desirable, call FAMPending before
     FAMNextEvent, and only call FAMNextEvent when FAMPending says an event is
     available.

     There are two ways to for applications to receive FAM events:

     1. The Select approach - The application selects on the file
	 descriptor returned from FAMOpen, in the FAMConnection structure.
	 When this file descriptor becomes active, the application calls
	 FAMPending to determine whether a complete event is ready, and
	 FAMNextEvent to retrieve the pending FAM event.

     2. The Polling approach - The application calls FAMPending
	 periodically (usually when the system is waiting for input).
	 When FAMPending returns 1, the application calls FAMNextEvent to
	 retrieve the pending FAM  event.

     FAMNextEvent reads any information that is on the fam socket, and returns
     it to the application in the form of a FAMEvent.

									Page 5

FAM(3X)								       FAM(3X)

     FAMNextEvent returns 1 if successful and -1 otherwise.

SEE ALSO
     fam(1M).

BUGS
     The FAMMoved event is not currently supported.

     FAMNextEvent may not initialize the FAMEvent's filename field for
     FAMEndExist and FAMAcknowledge events.  Use the request number to
     determine the file or directory to which those events refer.

     FAMErrno and FamErrlist are not set when errors occur.

     When a shell script is run, notification is generated for the shell
     executing the script, typically sh(1) or csh(1).

     Each process is limited to 1000 active requests at a time.

									Page 6

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