TACL Reference Manual

The TACL Environment
HP NonStop TACL Reference Manual—429513-018
6-3
Logging On
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Can run at a high PIN
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Can create a high-PIN process
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Can be created by a high-PIN process
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Can communicate with a high-PIN requester
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Can communicate with a high-PIN server
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Recognizes high-PIN process identifiers
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Does not default to run at a high PIN
Processes that run at high PINs cannot open and write to processes that do not allow
high-PIN openers. For example, a TACL process that runs at a high PIN cannot open a
process on a C-series node. Similarly, a TACL process on a C-series node cannot
open a high-PIN process. This limitation applies to any operation that accesses
process identifier information, such as alteration of priority. If you start a process and
try such communication with the new process, the new process terminates.
Logging On
To access a TACL process, you must log on. Before you log on, the only commands
TACL accepts are LOGON, FC, !, PAUSE, and TIME. If the system runs Safeguard
software, Safeguard can be set up so that it authenticates your user ID and requests
that TACL start logged-on. In this case, you do not need to log on to TACL.
TACL Initialization
When you log on, TACL creates a private segment file for you and invokes TACLINIT
(usually $SYSTEM.SYSnn.TACLINIT). TACLINIT begins initialization of TACL and
then searches in the same subvolume for the TACLSEGF segment file, which it
attaches and makes available under the directory :UTILS:TACL. Directories are
described in Using Directories on page 6-10.
TACL searches for TACLLOCL first in the SYSnn of the TACL PROGRAMFILE, and
then in $SYSTEM.SYSTEM.
You can ensure that there is always a system load recovery path by placing a
TACLLOCL in each SYSnn. If a TACLLOCL change causes any problem, reload the
system from the original SYSnn.
This method also offers a superior organizational scheme, because a TACLLOCL for
different system images often needs to have different TACL statements. Rather than
having complex version condition checking, each system image version can now have
its own TACLLOCL file.
If it finds the file, TACL invokes it as a macro. At this point, if your default subvolume
contains a TACLCSTM file, TACL invokes it as a macro. Your TACLCSTM file, which