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CHAPTER 6
6.
CHAIN COMMAND
The
CHAIN
command allows
predefined
procedures
to
be
automatically executed.
A procedure consists
or
any sequence
of MOOS command lines that has been put into a diskette
~ile,
known
as
a
CHAIN
rile.
Instead
Or obtaining successive
command lines from the console:
CHAIN
will
retch
commands
from
the
CHAIN
rile.
This
Teatu~e
allows complicated and
lengthy operations to be defined once, and then
invoked
any
number
or
times,
requiring
no operator intervention.
The
additional capabilities
of
conditional
directives
to
the
CHAIN command at both compilation and execution time, and the
capabilitq of string substitution!
permit an almost unlimited
number or applications to be handled by a CHAIN file.
6. 1
Use
The
CHAIN command is initially invoked by the following
command
1
ine:
CHAIN <name
1> [i<srg 1>" .... I<arg n>J
The only required
parameter
is
<name
1>,
the
rile
name
specification
or
the
diskette
rile
that
contains
the
procedure definition.
The CHAIN file, <name 1:>,
is given the
derault
sufrix
"CF" ,
permitting
the
file
name
to
be
identified
in
the
director~
listing at a glance
as
being
a
CHAIN
file.
The
default logical unit number
is
zero.
The
optional arguments, <arg i:> (i
=
1
to
n),
are
CHAIN
tag
definitions
which
can
be
used
to
modif~
the compilation,
content,
or ex ec uti on of
a
CHAIN
of i
le.
Two special forms of the CHAIN command line can be
used
to restart an aborted CHAIN process.
These command lines are
s
h
0
usn her e ,
but are des c,..
i
bed
i
n
d
eta i
1
ins e c t ion
6. 6.
CHAIN N*
CHAIN
*
CHAIN executes
a
compilation
phase
and
an
execution
phase.
In
the
compilation
phase,
<nam~
1> is read from
beg inn
i
rig
to
end.
An
i nteT"med
iate
f i
1 e,
CHAIN. SY: 0,
is
created
during
the
compilation.
The
intermediate
file
consists of lines to
be
used in the execution
phase
of
the
CHAIN
process.
This
file will
be
automatically deleted upon
the
subse~uent
successful
~ompletion
of the CHAIN
pro~ess.
During the execution phase, CHAIN
basically
intercepts
Page
06-01
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