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HLFSD(8)                    System Manager's Manual                   HLFSD(8)



NAME
       hlfsd - home-link file system daemon

SYNOPSIS
       hlfsd [ -fhnpvC ] [ -a alt_dir ] [ -c cache-interval ] [ -g group ] [
       -i reload-interval ] [ -l logfile ] [ -o mount-options ] [ -x
       log-options ] [ -D debug-options ] [ -P password-file ] [ linkname [
       subdir ] ]

DESCRIPTION
       Hlfsd is a daemon which implements a filesystem containing a symbolic
       link to subdirectory within a user's home directory, depending on the
       user which accessed that link.  It was primarily designed to redirect
       incoming mail to users' home directories, so that it can read from
       anywhere.

       Hlfsd operates by mounting itself as an NFS server for the directory
       containing linkname, which defaults to /hlfs/home. Lookups within that
       directory are handled by hlfsd, which uses the password map to
       determine how to resolve the lookup.  The directory will be created if
       it doesn't already exist.  The symbolic link will be to the accessing
       user's home directory, with subdir appended to it.  If not specified,
       subdir defaults to .hlfsdir. This directory will also be created if it
       does not already exist.

       A SIGTERM sent to hlfsd will cause it to shutdown.  A SIGHUP will flush
       the internal caches, and reload the password map.  It will also close
       and reopen the log file, to enable the original log file to be removed
       or rotated.  A SIGUSR1 will cause it to dump its internal table of user
       IDs and home directories to the file /usr/tmp/hlfsd.dump.XXXXXX.

OPTIONS
       -a alt_dir
              Alternate directory.  The name of the directory to which the
              symbolic link returned by hlfsd will point, if it cannot access
              the home directory of the user.  This defaults to /var/hlfs.
              This directory will be created  if it doesn't exist.  It is
              expected that either users will read these files, or the system
              administrators will run a script to resend this "lost mail" to
              its owner.

       -c cache-interval
              Caching interval.  Hlfsd will cache the validity of home
              directories for this interval, in seconds.  Entries which have
              been verified within the last cache-interval seconds will not be
              verified again, since the operation could be expensive, and the
              entries are most likely still valid.  After the interval has
              expired, hlfsd will re-verify the validity of the user's home
              directory, and reset the cache time-counter.  The default value
              for cache-interval is 300 seconds (5 minutes).

       -f     Force fast startup.  This option tells hlfsd to skip startup-
              time consistency checks such as existence of mount directory,
              alternate spool directory, symlink to be hidden under the mount
              directory, their permissions and validity.

       -g group
              Set the special group HLFS_GID to group. Programs such as from
              or comsat, which access the mailboxes of other users) must be
              setgid HLFS_GID to work properly.  The default group is "hlfs".
              If no group is provided, and there is no group "hlfs", this
              feature is disabled.

       -h     Help.  Print a brief help message, and exit.

       -i reload-interval
              Map-reloading interval.  Each reload-interval seconds, hlfsd
              will reload the password map.  Hlfsd needs the password map for
              the UIDs and home directory pathnames.  Hlfsd schedules a
              SIGALRM to reload the password maps.  A SIGHUP sent to hlfsd
              will force it to reload the maps immediately.   The default
              value for reload-interval is 900 seconds (15 minutes.)

       -l logfile
              Specify a log file to which hlfsd will record events.  If
              logfile is the string syslog then the log messages will be sent
              to the system log daemon by syslog(3), using the LOG_DAEMON
              facility.  This is also the default.

       -n     No verify.  Hlfsd will not verify the validity of the symbolic
              link it will be returning, or that the user's home directory
              contains sufficient disk-space for spooling.  This can speed up
              hlfsd at the cost of possibly returning symbolic links to home
              directories which are not currently accessible or are full.  By
              default, hlfsd validates the symbolic-link in the background.
              The -n option overrides the meaning of the -c option, since no
              caching is necessary.

       -o mount-options
              Mount options.  Mount options which hlfsd will use to mount
              itself on top of dirname. By default, mount-options is set to
              "ro".  If the system supports symbolic-link caching, default
              options are set to "ro,nocache".

       -p     Print PID.  Outputs the process-id of hlfsd to standard output
              where it can be saved into a file.

       -v     Version.  Displays version information to standard error.

       -x log-options
              Specify run-time logging options.  The options are a comma
              separated list chosen from: fatal, error, user, warn, info, map,
              stats, all.

       -C     Force hlfsd to run on systems that cannot turn off the NFS
              attribute-cache.  Use of this option on those systems is
              discouraged, as it may result in loss or mis-delivery of mail.
              The option is ignored on systems that can turn off the
              attribute-cache.

       -D log-options
              Select from a variety of debugging options.  Prefixing an option
              with the string no reverses the effect of that option.  Options
              are cumulative.  The most useful option is all. Since this
              option is only used for debugging other options are not
              documented here.  A fuller description is available in the
              program source.  A SIGUSR1 sent to hlfsd will cause it to dump
              its internal password map to the file
              /usr/tmp/hlfsd.dump.XXXXXX.

       -P password-file
              Read the user-name, user-id, and home directory information from
              the file password-file. Normally, hlfsd will use getpwent(3) to
              read the password database.  This option allows you to override
              the default database, and is useful if you want to map users'
              mail files to a directory other than their home directory.  Only
              the username, uid, and home-directory fields of the file
              password-file are read and checked.  All other fields are
              ignored.  The file password-file must otherwise be compliant
              with Unix System 7 colon-delimited format passwd(5).

FILES
       /hlfs
            directory under which hlfsd mounts itself and manages the symbolic
            link home.

       .hlfsdir
            default sub-directory in the user's home directory, to which the
            home symbolic link returned by hlfsd points.

       /var/hlfs
            directory to which home symbolic link returned by hlfsd points if
            it is unable to verify the that user's home directory is
            accessible.

SEE ALSO
       mail(1), getgrent(3), getpwent(3), passwd(5), amd(8), cron(8),
       mount(8), sendmail(8), umount(8).

       HLFSD: Delivering Email to Your $HOME, in Proc. LISA-VII, The 7th
       Usenix System Administration Conference, November 1993.

       ``am-utils'' info(1) entry.

       Linux NFS and Automounter Administration by Erez Zadok, ISBN
       0-7821-2739-8, (Sybex, 2001).

       http://www.am-utils.org

AUTHORS
       Erez Zadok <ezkATcs.edu>, Computer Science Department, Stony
       Brook University, Stony Brook, New York, USA.  and Alexander Dupuy
       <dupuyATsmarts.com>, System Management ARTS, White Plains, New York,
       USA.

       Other authors and contributors to am-utils are listed in the AUTHORS
       file distributed with am-utils.



                               14 September 1993                      HLFSD(8)