Open System Services Shell and Utilities Reference Manual (G06.25+, H06.03+)

gtacl(1) OSS Shell and Utilities Reference Manual
• You need not distinguish among TACL built-in functions, TACL macros, or programs
external to TACL.
• You can use TACL RUN option syntax to direct input or output to Guardian
files (such as
spooler locations) that are not available through shell redirection.
Using the -c or -cv option to run a Guardian process has the following disadvantages:
• You cannot redirect standard input using the shell.
• If you do not need TACL facilities, these options add the unnecessary overhead of TACL
process creation.
Using the -p option to run a Guardian process has the following advantages:
• It runs the program without the overhead of TACL process creation.
• There are no restrictions on redirection of OSS files using the shell.
Using the -p option to run a Guardian process has the following disadvantages:
• TACL facilities (such as built-in functions or macros) cannot be used.
Redirecting Input or Output
The gtacl process does not have its own run options for redirecting output. Instead, standard
/bin/sh redirection operators can be used to redirect the input or output of the gtacl process for
any file that can be opened using the OSS-environment open() function.
You cannot use the OSS shell to redirect input or output for files that can be opened only using
the Guardian file system (with the FILE_OPEN_ procedure call). For such files, the gtacl -c
command or -cv command option must be used with TACL file redirection. For example, the fol-
lowing command fails because the OSS shell cannot directly open the Guardian spooler process:
gtacl -p tgal < /G/vol/subvol/file > /G/S/#TITAN
Instead, the following command must be used:
gtacl -c ’tgal /IN $vol.subvol.file, OUT $S.#TITAN/’
Many Guardian processes allow input or output from a process file. The gtacl process uses this
feature by running as a named process and passing its own name in place of the OSS standard
files that cannot be opened by the Guardian FILE_OPEN_ procedure call. For example, if gtacl
is invoked with the following command and runs with a system-generated process name of
$X123:
gtacl -c ’fileinfo $vol.subvol.*’ > fileinfo.output
then the gtacl process runs TACL with an IN file named $X123.#CMD and an OUT file named
$X123.#OUT. When TACL first reads from $X123.#CMD, gtacl returns the string fileinfo
$vol.subvol.*; on the next read, gtacl returns an end-of-file indication. Any output from TACL
to $X123.#OUT is written by gtacl to its own OSS environment standard output file, which has
been connected to the OSS environment file fileinfo.output by shell redirection.
Input/OutputFiltering
The gtacl process automatically converts line endings for data passing between the two environ-
ments. When gtacl encounters a newline indicator in input from the OSS environment, it
removes that character and forwards the line as a separate record to the Guardian environment.
When gtacl encounters the end of a record in input from the Guardian environment, it forwards
the line with a newline indicator to the OSS environment. This conversion is the primary filter-
ing done to the data.
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