=head1 NAME

gbch-start - start batch scheduler

gbch-conn - connect to host

gbch-disconn - disconnect from host

btdst - adjust for daylight saving time

=head1 SYNOPSIS

B<gbch-start>
[ I<-options> ]

B<gbch-conn>
I<hostname>

B<gbch-disconn>
I<hostname>

B<gbch-dst>
[ I<-R> ]
I<startdate>
I<enddate>
I<adjustment>

=head1 DESCRIPTION

B<gbch-start> initiates the B<GNUbatch> batch scheduler system, by
starting the processes btsched(8) and xbnetserv(8).

Optional arguments enable the initial sizes of shared memory to be
determined and also an initial value for the C<LOADLEVEL> variable,
which may determine how many jobs (possibly none) start up as soon as
B<GNUbatch> comes up.

B<gbch-conn> instructs the B<GNUbatch> scheduler to attempt to raise a
connection to the given host, which should be specified in the file
F<gnubatch.hosts>, and not currently active.

B<gbch-disconn> instructs the B<GNUbatch> scheduler to close a connection
to the given host, which should be specified in the file
F</etc/>, and currently active.

B<gbch-dst> adjusts all jobs between the specified start and end dates
and times by adding the specified (possibly signed) I<adjustment> in
seconds to it.

The dates and times may be specified in the forms

	dd/mm
	mm/dd
or

	yy/mm/dd

Which of the first two forms is chosen is taken from the existing time
zone. For time zones greater or equal to 4 West from GMT, the C<mm/dd>
form is chosen, otherwise C<dd/mm>.

The dates may be followed by a comma and a time in the form C<hh:mm>,
otherwise midnight is assumed.

When working out what to do, remember that Unix internal time is based
upon Greenwich Mean Time (GMT), it is the I<display> which changes, so
that the effect of moving the clocks forward is to make the times
(held as GMT) appear later than they did before.

A negative adjustment is I<subtracted> from the time, making jobs run
sooner. This is therefore appropriate when the clocks go forward at
the start of the summer time. Likewise a positive adjustment should be
used at the end of summer time.

The optional argument B<-R> tries to apply the option to all exported
remote jobs, but this really is not recommended as the local jobs on
those hosts will be unaffected probably leaving the users on those
machines confused.

=head1 OPTIONS

Note that everything in this section only applies to B<gbch-start>.

Note that the order of treatment, letters and keywords described below
may be modified by editing the file F<btrest.help> -
see btsyntax(5).

The environment variable on which options are supplied is C<GBCH_START> and the
environment variable to specify the help file is C<BTRESTCONF>.

=over 4

=item -? or +explain

causes a summary of the other options to be displayed without taking
further action.

=item -l I<number> or +initial-load-level I<number>

set the initial value of the C<LOADLEVEL> variable, which controls the
total load level of running jobs to the specified number (usually
zero). If this option is not specified, then the value is unchanged
from its initial value saved by the scheduler when it was last shut
down.

If the B<GNUbatch> scheduler is already running, this option has no
effect.

=item -j I<number> or +initial-job-size I<number>

Allocate shared memory initially for the specified I<number> of
jobs. This is necessary in some situations where other applications
use up the system limit of shared memory and it is not possible to
allocate further after the system has been running for some time.

If the B<gnubatch> scheduler is already running, this option has no
effect.

=item -v I<number> or +initial-var-size I<number>

Allocate shared memory initially for the specified I<number> of
variables. This is necessary in some situations where other
applications use up the system limit of shared memory and it is not
possible to allocate further after the system has been running for
some time.

If the B<GNUbatch> scheduler is already running, this option has no
effect.

=item +freeze-current

Save all the current options in a F<.gnubatch> file in the current
directory. If this option is specified, there is no further action.

=item +freeze-home

Save all the current options in a F<.gnubatch> file in the user's home
directory. If this option is specified, there is no further action.

=back

=head1 FILES

F<~/.gnubatch>
configuration file (home directory)

F<.gnubatch>
configuration file (current directory)

F<btrest.help>
message file

=head1 ENVIRONMENT

=over 4

=item GBCH_START

space-separated options to override defaults for B<gbch-start>

=item BTRESTCONF

location of alternative help file.

=back

=head1 SEE ALSO

gbch-quit(1),
btsyntax(5),
gnubatch.conf(5),
gnubatch.hosts(5),
btsched(8),
xbnetserv(8).

=head1 DIAGNOSTICS

Various diagnostics are read and printed as required from the message
file F<btrest.help>.

=head1 COPYRIGHT

Copyright (c) 2009 Free Software Foundation, Inc.
This is free software. You may redistribute copies of it under the
terms of the GNU General Public License
<http://www.gnu.org/licenses/gpl.html>.
There is NO WARRANTY, to the extent permitted by law.

=head1 AUTHOR

John M Collins, Xi Software Ltd.

=cut

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