path: root/contrib/amd/hlfsd/hlfsd.8

.\"
.\" Copyright (c) 1997-2006 Erez Zadok
.\" Copyright (c) 1989 Jan-Simon Pendry
.\" Copyright (c) 1989 Imperial College of Science, Technology & Medicine
.\" Copyright (c) 1989 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Jan-Simon Pendry at Imperial College, London.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgment:
.\"      This product includes software developed by the University of
.\"      California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\"
.\" $Id: hlfsd.8,v 1.11.2.1 2006/01/02 18:48:25 ezk Exp $
.\"
.\" HLFSD was written at Columbia University Computer Science Department, by
.\" Erez Zadok <ezk@cs.columbia.edu> and Alexander Dupuy <dupuy@smarts.com>
.\" It is distributed under the same terms and conditions as AMD.
.\"
.TH HLFSD 8 "14 September 1993"
.SH NAME
hlfsd \- home-link file system daemon
.SH SYNOPSIS
.B hlfsd
[
.B \-fhnpvC
] [
.BI \-a " alt_dir"
] [
.BI \-c " cache-interval"
] [
.BI \-g " group"
] [
.BI \-i " reload-interval"
] [
.BI \-l " logfile"
] [
.BI \-o " mount-options"
] [
.BI \-x " log-options"
] [
.BI \-D " debug-options"
] [
.BI \-P " password-file"
]
[
.I linkname
.RI [ " subdir " ]
]
.SH DESCRIPTION
.B 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.
.LP
.B Hlfsd
operates by mounting itself as an
.SM NFS
server for the directory containing
.IR linkname ,
which defaults to
.BR /hlfs/home .
Lookups within that directory are handled by
.BR 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
.I subdir
appended to it.  If not specified,
.I subdir
defaults to
.BR .hlfsdir .
This directory will also be created if it does not already exist.
.LP
A SIGTERM sent to
.B 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
.BR /usr/tmp/hlfsd.dump.XXXXXX .
.SH OPTIONS
.TP
.BI \-a " alt_dir"
Alternate directory.  The name of the directory to which
the symbolic link returned by
.B hlfsd
will point, if it cannot access the home directory of the user.  This
defaults to
.BR /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.
.TP
.BI \-c " cache-interval"
Caching interval.
.B Hlfsd
will cache the validity of home directories for this interval, in
seconds.  Entries which have been verified within the last
.I 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,
.B hlfsd
will re-verify the validity of the user's home directory, and
reset the cache time-counter.  The default value for
.I cache-interval
is 300 seconds (5 minutes).
.TP
.B \-f
Force fast startup.  This option tells
.B 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.
.TP
.BI \-g " group"
Set the special group HLFS_GID to
.IR group .
Programs such as
.B from
or
.BR 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.
.TP
.B \-h
Help.  Print a brief help message, and exit.
.TP
.BI \-i " reload-interval"
Map-reloading interval.  Each
.I reload-interval
seconds,
.B hlfsd
will reload the password map.
.B Hlfsd
needs the password map for the UIDs and home directory pathnames.
.B Hlfsd
schedules a SIGALRM to reload the password maps.  A SIGHUP sent to
.B hlfsd
will force it to reload the maps immediately.   The default
value for
.I reload-interval
is 900 seconds (15 minutes.)
.TP
.BI \-l " logfile"
Specify a log file to which
.B hlfsd
will record events.  If
.I logfile
is the string
.B syslog
then the log messages will be sent to the system log daemon by
.IR syslog (3),
using the LOG_DAEMON facility.
This is also the default.
.TP
.B \-n
No verify.
.B 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
.B hlfsd
at the cost of possibly returning symbolic links to home
directories which are not currently accessible or are full.
By default,
.B hlfsd
validates the symbolic-link in the background.
The
.B \-n
option overrides the meaning of the
.B \-c
option, since no caching is necessary.
.TP
.BI \-o " mount-options"
Mount options.  Mount options which
.B hlfsd
will use to mount itself on top of
.I dirname.
By default,
.IR mount-options
is set to "ro".  If the system supports symbolic-link caching, default
options are set to "ro,nocache".
.TP
.B \-p
Print PID.
Outputs the process-id of
.B hlfsd
to standard output where it can be saved into a file.
.TP
.B \-v
Version.  Displays version information to standard error.
.TP
.BI \-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.
.TP
.BI \-C
Force
.B 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.
.TP
.BI \-D " log-options"
Select from a variety of debugging options.  Prefixing an
option with the string
.B no
reverses the effect of that option.  Options are cumulative.
The most useful option is
.BR 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
.B hlfsd
will cause it to dump its internal password map to the file
.BR /usr/tmp/hlfsd.dump.XXXXXX .
.TP
.BI \-P " password-file"
Read the user-name, user-id, and home directory information from the file
.I password-file.
Normally,
.B hlfsd
will use
.IR 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
.I password-file
are read and checked.  All other fields are ignored.  The file
.I password-file
must otherwise be compliant with Unix System 7 colon-delimited format
.IR passwd (4).
.SH FILES
.TP 5
.B /hlfs
directory under which
.B hlfsd
mounts itself and manages the symbolic link
.BR home .
.TP 5
.B .hlfsdir
default sub-directory in the user's home directory, to which the
.B home
symbolic link returned by
.B hlfsd
points.
.TP 5
.B /var/hlfs
directory to which
.B home
symbolic link returned by
.B hlfsd
points if it is unable to verify the that
user's home directory is accessible.
.SH "SEE ALSO"
.BR amd (8),
.BR automount (8),
.BR cron(8),
.BR getgrent (3),
.BR getpwent (3),
.BR mail(1),
.BR mnttab (4),
.BR mount (8),
.BR mtab (5),
.BR passwd (4),
.BR sendmail (8),
.BR umount (8).
.LP
.IR "HLFSD: Delivering Email to Your $HOME" ,
in
.IR "Proc. LISA-VII, The 7th Usenix System Administration Conference" ,
November 1993.
.LP
``am-utils''
.BR info (1)
entry.
.LP
.I "Linux NFS and Automounter Administration"
by Erez Zadok, ISBN 0-7821-2739-8, (Sybex, 2001).
.LP
.I http://www.am-utils.org
.SH 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.
.P
Other authors and contributors to am-utils are listed in the
.B AUTHORS
file distributed with am-utils.