Provided by: am-utils_6.2+rc20110530-3.2ubuntu2_amd64 
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(4).
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), mnttab(4), passwd(4), mtab(5), amd(8), automount(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 <ezk@cs.sunysb.edu>, Computer Science Department, Stony Brook University, Stony Brook, New
York, USA. and Alexander Dupuy <dupuy@smarts.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)