ypxfr.8yp

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)ypxfr.8yp	8.1	9/11/90
./" Last edited by Jeff J. 6/24/86
.TH ypxfr 8yp
.SH Name
ypxfr \- transfer a yellow pages (YP) map from a YP server to the local host.
.SH Syntax
.B ypxfr
[
.B \-f
] 
[ \fB-h \fIhost\fR ]
[ \fB-d \fIdomain\fR ]
[
.B \-c
] 
[ \fB-C\fR
.I "tid prog ipadd port"
]
.I mapname
.SH Description
.NXR "ypxfr command"
.NXA "yppush command" "ypxfr command"
.NXR "YP map" "transferring"
The
.PN ypxfr 
command moves a YP map, specified by the 
.I mapname 
argument, to the local host by making use of normal YP services.
It creates a temporary map in the directory 
.PN /etc/yp/domain
(which must already exist),
fills it by enumerating the map's entries, obtains the
map parameters (master and order number) and loads them into the map.
Once 
.PN ypxfr 
has accomplished these tasks,
it deletes any old versions of the map and moves the 
temporary map to the real mapname.
.PP
If 
.PN ypxfr 
is run interactively, it writes its output to the terminal.
However, if it is invoked without a controlling terminal, and if the
log file 
.PN /etc/yp/ypxfr.log
exists, it will append all its output to that file.  Since 
.PN ypxfr 
is most often run from 
.PN /usr/lib/crontab ,
or by
.PN ypserv ,
the log file can be used to retain a record of what was attempted, 
and the results.
.PP
For consistency between servers,
.PN ypxfr 
should be run periodically for every map in the YP database. 
Different maps change at different
rates:  the 
.PN services.byname
map may not change for months at a time, for instance, and may 
therefore be checked only once a day. It is possible 
that 
.PN mail.aliases 
or 
.PN hosts.byname
changes several times per day.  In such a case, it is appropriate to
check hourly for updates.   A 
.MS cron 8 
entry should be used to perform periodic updates automatically on YP
server machines only.
Rather than having a separate
.PN cron
entry for each map, commands can be grouped to update several maps 
in a shell script.  Examples (mnemonically named) are in 
.PN /etc/yp: 
.PN ypxfr_1perday.sh, 
.PN ypxfr_2perday.sh, 
and 
.PN ypxfr_1perhour.sh .
They can serve as reasonable first cuts.
.PP
See 
.MS ypfiles 5yp  
and 
.MS ypserv 8yp 
for an overview of the yellow pages.
.SH Options
.IP "\fB\-f\fR" 1i
Force the transfer to occur even if the version at the MASTER is not 
more recent than the local version.
.IP "\fB\-c\fR" 1i
Do not send a "Clear current map" request to the local 
.PN ypserv 
process.  This flag should be used if 
.PN ypserv 
is not running locally at the time when
.PN ypxfr 
is running.
Otherwise,
.PN ypxfr 
will report that it can not talk to the local
.PN ypserv, 
and the transfer will fail.
.IP "\fB\-h \fIhost\fR"
Get the map from
.I host,
regardless of which map is the master.  If 
.I host 
is not specified,
.PN ypxfr 
will ask the YP service for the name of the master, and try to get the 
map from there.
The
.I host
option can be a name or an internet address in the form 
.I "a.b.c.d".
.IP "\fB\-d \fIdomain\fR"
Specify a domain other than the default domain.
.IP "\fB\-C \fItid prog ipadd port\fR"
This option is only for use by
.PN ypserv .
When  
.PN ypserv
invokes 
.PN ypxfr, 
it specifies that 
.PN ypxfr
should call back a
.PN yppush
process at the host with IP address
.I ipaddr,
registered as program number
.I prog,
listening on port
.I port,
and waiting for a response to transaction
.I tid.
.SH Files
.PN /etc/yp/ypxfr.log
.br
.PN /etc/yp/ypxfr_1perday.sh
.br
.PN /etc/yp/ypxfr_2perday.sh
.br
.PN /etc/yp/ypxfr_1perhour.sh
.br
.PN /usr/lib/crontab
.SH See Also
ypfiles(5yp), cron(8), yppush(8yp), ypserv(8yp), ypsetup(8yp)