Open System Services Porting Guide (G06.24+, H06.03+)

Migrating Guardian Applications to the OSS
Environment
Open System Services Porting Guide—520573-006
8-21
Using OSH From TACL
•
Using PROCESS_SPAWN_ in a Guardian Program on page 8-22
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Using the Guardian LISTNER Program on page 8-23
Using OSH From TACL
The OSH command can be used to run a process in the OSS environment from the
Guardian environment. The OSH command is a Guardian program that spawns an
OSS process within the same node, allowing you to specify the environment and initial
process attributes of the child process. Using the -c option, you can submit a
command to the OSS child process, as follows:
osh -c command_string
where the command string can be any valid OSS shell command, OSS utility name, or
script file pathname. Parameters to be processed by the named command, utility, or
script can also be included. Standard I/O streams can be redirected from or to OSS
files. Input and output can be redirected to Guardian processes and EDIT files by using
the OSSTTY facility. (OSSTTY can be invoked on the OSH command line. See the
Open System Services Programmer’s Guide for more information about OSSTTY). A
specific OSS program can be run by using the -p option, for example:
osh -p pathname arg1 arg2 ... argn
In this case, the specified program is run as a child process from the TACL prompt. By
default, the OSH command without arguments creates a child process running the
login shell. The Guardian DEFINEs are inherited by OSH and resulting child
processes. All Guardian PARAMs are converted into OSS environment variables for
the child process. More details on starting up an OSS program using the OSH
command from TACL are available in the osh(1) reference page either online or in
the Open System Services Shell and Utilities Reference Manual.
Using system() in a Guardian Program
OSS programs can be started from the Guardian environment in a programmatic way
by using the system() Guardian C run-time routine to run the OSH command, which
in turn can run an OSS command. When the OSH command is run programmatically,
the TACL RUN options IN and OUT must be specified. More details on starting up an
OSS program using the system() function is available in the system(3) reference
page either online or in the Open System Services Library Calls Reference Manual.
Example 8-1 provides sample code: the command string passed to the Guardian
program can be any valid OSS shell command.
The OSS command line must be given to the Guardian RUNOSSP command within
double quotes (" ") to make sure there is no interpretation of special characters within
the command string. An example follows:
run runossp "ls -l /home/stu01 > listfile"
Here the output file listfile is produced in the OSS file system. An OSS script can
also be run using the RUNOSSP utility from the TACL command interpreter.