Sun Microsystems Sun Workstation 100U System Manager's Manual page 337

SendmaU Inatallatlon and OperatloD Guld.
'I
lusr Ilib/sendmail -bi
If the "D" option is speciBed in the conB,uration, IfmtimtJil will rebuild the alias
database automatically if p088ible when it is out of date. The conditions under which it
wiD do this are:
(1) The
DBM
version 01 the database
is
mode 666. -or-
(2)
SendmtJu is running setuid to root.
Auto-rebuild can be dangerous on heavily loaded machines with large alias files; if it
might take more than five minutes to rebuild the databue, there is a chance that
several processes will start the rebuild process simultaneously.
1.4.1. Potential problema
There are a number 01 problems that can occur with the alias database. They all
result from a BendmtJu proce88 accessing the
DBM
version while it is only partially
built. This can happen under two circumstances: One process accesses the database
while another process is rebuilding it, or the process rebuilding the database dies (due
to being killed or a system crash) belore completing the rebuild.
Send mail has two techniques to try to relieve these problems. First, it ignores
interrupts while rebuilding the database; this avoids the problem of someone aborting
the process leaving a partially rebuilt database. Second, at the end 01 the rebuild it
adds an alias of the fonn
0:0
(which is not normally legal). Belore ,endmail wiD access the database, it checks
to
insure that this entry exists
1
•
It will wait up to Bve minutes lor this entry to appear, at
which point it wiD force a rebuild itsell
2
•
1.4.3. List owner.
If an error occurs on sending to a certain address, say
"z',
,endmtJil will look lor
an alias of the form "owner-z' to receive the erron. This is typically uselul lor a mail-
ing list where the submitter 01 the list has no control over the maintanence 01 the list
itself; in this case the list maintainer would be the owner of the list. For example:
unix-wizards: ericGucbarpa, wnjGmonet, n08uchuser,
samCmatisse
owner-unix-wizards: ericGucbarpa
would cause "ericOucbarpa" to get the error that wiD occur when someone sends to
unix-wizards due to the inclusion or "n08uchuser"
OD
the list.
2.5. Per-User Forwardln, (.forward FUea)
As
an alternative to the alias database, any user may put a file with the name ".for-
ward" in his or her home directory. If this file exists, ,endmtJil redirects mail lor that user
to the list of addresses listed in the .forward file. For example, if the home directory for
user "mckusick" has a .forward file with contents:
mckusickGernie
kirk<Ocalder
then any mail arriving for "mckusick" will be redirected to the speci8ed accounts.
IThe
CI
a" option is required ill the configuntio. for this actio.
to
occur. This should llorm:t.lIJ be specified Dlllees
you a.re ronninc del'tlermtl.1 in pa.rallel with ,eRdm.iI.
~ote:
the "D"
option must be specified in
the confiputioll lIe for this operatioa to occur.
Version 4.1
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