z/OS V1R9.0 UNIX System Services Command ... - Christian Grothoff

BPXBATCH
Files
_BPX_BATCH_SPAWN causes BPXBATCH to use SPAWN instead of
fork/exec and allows data definitions to be carried over into the spawned
process. When _BPX_BATCH_SPAWN is set to YES, spawn will be used. If it
is set to NO, which is equivalent to the default behavior, fork/exec will be used
to execute the program.
If _BPX_BATCH_SPAWN is set to YES, then you must consider two other
environment variables that affect spawn (BPX1SPN):
v _BPX_SHAREAS = YES|NO|REUSE|MUST
When YES or REUSE, the child process created by spawn will run in the
same address space. Failure to meet these conditions will result in a spawn
failure when MUST is used. For more detail about these restrictions see the
descriptions of the spawn() function and BPX1SPN callable service in z/OS
UNIX System Services Programming: Assembler Callable Services
Reference:
– The invoker must have an UID of 0 to issue a SH request
– The child process is not setuid or setgid to a value different from the
parent
– The spawned file name is not an external link or a sticky bit file
– The parent has enough resources to allow the child process to reside in
the same address space
– The NOSHAREAS extended attribute is not set
When no, the child and parent run in separate address spaces.
v _BPX_SPAWN_SCRIPT=YES
Spawn will recognize a header in the first line of a z/OS UNIX file that
indicates the file to be executed and its first set of arguments. This header
will only be recognized when a z/OS UNIX file is not found in an executable
format. The format of the header is as follows:
#! Path String
where #! is the file magic number. The magic number indicates that the first
line of a file is a special header that contains the name of the program to be
executed and any argument data to be supplied to it.
When _BPX_SPAWN_SCRIPT=yes, spawn will first recognize the file magic
number and will process the file accordingly. If the file magic number is not
found in the file’s first line, spawn will treat the specified file as a shell script
and will invoke the shell to run the shell script.
For more information about spawn, see BPX1SPN in z/OS UNIX System
Services Programming: Assembler Callable Services Reference.
13. When using BPXBATCH with the SH parameter, environment variables
specified in the STDENV DD are overridden by those specified in /etc/profile
and .profile (which overrides /etc/profile). This is because SH causes
BPXBATCH to execute a login shell which runs the /etc/profile script and runs
the user’s .profile.
v SYS1.LINKLIB(BPXMBATC) is the BPXBATCH program location.
v The stdin default is /dev/null.
v The stdout default is /dev/null.
v The stderr default is the value of stdout. If all defaults are accepted, stderr is
/dev/null.
v stdenv default is /dev/null.
898 z/OS V1R9.0 UNIX System Services Command Reference