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.