1HLFSD(8) System Manager's Manual HLFSD(8)
2
6 hlfsd - home-link file system daemon
7
9 hlfsd [ -fhnpvC ] [ -a alt_dir ] [ -c cache-interval ] [ -g group ] [
10 -i reload-interval ] [ -l logfile ] [ -o mount-options ] [ -x log-
11 options ] [ -D debug-options ] [ -P password-file ] [ linkname [ subdir
12 ] ]
13
15 Hlfsd is a daemon which implements a filesystem containing a symbolic
16 link to subdirectory within a user's home directory, depending on the
17 user which accessed that link. It was primarily designed to redirect
18 incoming mail to users' home directories, so that it can read from any‐
19 where.
20 Hlfsd operates by mounting itself as an NFS server for the directory
22 containing linkname, which defaults to /hlfs/home. Lookups within that
23 directory are handled by hlfsd, which uses the password map to deter‐
24 mine how to resolve the lookup. The directory will be created if it
25 doesn't already exist. The symbolic link will be to the accessing
26 user's home directory, with subdir appended to it. If not specified,
27 subdir defaults to .hlfsdir. This directory will also be created if it
28 does not already exist.
29 A SIGTERM sent to hlfsd will cause it to shutdown. A SIGHUP will flush
31 the internal caches, and reload the password map. It will also close
32 and reopen the log file, to enable the original log file to be removed
33 or rotated. A SIGUSR1 will cause it to dump its internal table of user
34 IDs and home directories to the file /usr/tmp/hlfsd.dump.XXXXXX.
35
37 -a alt_dir
38 Alternate directory. The name of the directory to which the
39 symbolic link returned by hlfsd will point, if it cannot access
40 the home directory of the user. This defaults to /var/hlfs.
41 This directory will be created if it doesn't exist. It is
42 expected that either users will read these files, or the system
43 administrators will run a script to resend this "lost mail" to
44 its owner.
45 -c cache-interval
47 Caching interval. Hlfsd will cache the validity of home direc‐
48 tories for this interval, in seconds. Entries which have been
49 verified within the last cache-interval seconds will not be ver‐
50 ified again, since the operation could be expensive, and the
51 entries are most likely still valid. After the interval has
52 expired, hlfsd will re-verify the validity of the user's home
53 directory, and reset the cache time-counter. The default value
54 for cache-interval is 300 seconds (5 minutes).
55 -f Force fast startup. This option tells hlfsd to skip startup-
57 time consistency checks such as existence of mount directory,
58 alternate spool directory, symlink to be hidden under the mount
59 directory, their permissions and validity.
60 -g group
62 Set the special group HLFS_GID to group. Programs such as from
63 or comsat, which access the mailboxes of other users) must be
64 setgid HLFS_GID to work properly. The default group is "hlfs".
65 If no group is provided, and there is no group "hlfs", this fea‐
66 ture is disabled.
67 -h Help. Print a brief help message, and exit.
69 -i reload-interval
71 Map-reloading interval. Each reload-interval seconds, hlfsd
72 will reload the password map. Hlfsd needs the password map for
73 the UIDs and home directory pathnames. Hlfsd schedules a
74 SIGALRM to reload the password maps. A SIGHUP sent to hlfsd
75 will force it to reload the maps immediately. The default
76 value for reload-interval is 900 seconds (15 minutes.)
77 -l logfile
79 Specify a log file to which hlfsd will record events. If log‐
80 file is the string syslog then the log messages will be sent to
81 the system log daemon by syslog(3), using the LOG_DAEMON facil‐
82 ity. This is also the default.
83 -n No verify. Hlfsd will not verify the validity of the symbolic
85 link it will be returning, or that the user's home directory
86 contains sufficient disk-space for spooling. This can speed up
87 hlfsd at the cost of possibly returning symbolic links to home
88 directories which are not currently accessible or are full. By
89 default, hlfsd validates the symbolic-link in the background.
90 The -n option overrides the meaning of the -c option, since no
91 caching is necessary.
92 -o mount-options
94 Mount options. Mount options which hlfsd will use to mount
95 itself on top of dirname. By default, mount-options is set to
96 "ro". If the system supports symbolic-link caching, default
97 options are set to "ro,nocache".
98 -p Print PID. Outputs the process-id of hlfsd to standard output
100 where it can be saved into a file.
101 -v Version. Displays version information to standard error.
103 -x log-options
105 Specify run-time logging options. The options are a comma sepa‐
106 rated list chosen from: fatal, error, user, warn, info, map,
107 stats, all.
108 -C Force hlfsd to run on systems that cannot turn off the NFS
110 attribute-cache. Use of this option on those systems is dis‐
111 couraged, as it may result in loss or mis-delivery of mail. The
112 option is ignored on systems that can turn off the attribute-
113 cache.
114 -D log-options
116 Select from a variety of debugging options. Prefixing an option
117 with the string no reverses the effect of that option. Options
118 are cumulative. The most useful option is all. Since this
119 option is only used for debugging other options are not docu‐
120 mented here. A fuller description is available in the program
121 source. A SIGUSR1 sent to hlfsd will cause it to dump its
122 internal password map to the file /usr/tmp/hlfsd.dump.XXXXXX.
123 -P password-file
125 Read the user-name, user-id, and home directory information from
126 the file password-file. Normally, hlfsd will use getpwent(3) to
127 read the password database. This option allows you to override
128 the default database, and is useful if you want to map users'
129 mail files to a directory other than their home directory. Only
130 the username, uid, and home-directory fields of the file pass‐
131 word-file are read and checked. All other fields are ignored.
132 The file password-file must otherwise be compliant with Unix
133 System 7 colon-delimited format passwd(4).
134
136 /hlfs
137 directory under which hlfsd mounts itself and manages the symbolic
138 link home.
139 .hlfsdir
141 default sub-directory in the user's home directory, to which the
142 home symbolic link returned by hlfsd points.
143 /var/hlfs
145 directory to which home symbolic link returned by hlfsd points if
146 it is unable to verify the that user's home directory is accessi‐
147 ble.
148
150 mail(1), getgrent(3), getpwent(3), mnttab(4), passwd(4), mtab(5),
151 amd(8), automount(8), cron(8), mount(8), sendmail(8), umount(8).
152 HLFSD: Delivering Email to Your $HOME, in Proc. LISA-VII, The 7th
154 Usenix System Administration Conference, November 1993.
155 ``am-utils'' info(1) entry.
157 Linux NFS and Automounter Administration by Erez Zadok, ISBN
159 0-7821-2739-8, (Sybex, 2001).
160 http://www.am-utils.org
162
164 Erez Zadok <ezk@cs.sunysb.edu>, Computer Science Department, Stony
165 Brook University, Stony Brook, New York, USA. and Alexander Dupuy
166 <dupuy@smarts.com>, System Management ARTS, White Plains, New York,
167 USA.
168 Other authors and contributors to am-utils are listed in the AUTHORS
170 file distributed with am-utils.
171 14 September 1993 HLFSD(8)