The following conditions must be satisfied before POSIX can be started by a user with the SUBSYSTEM-MANAGEMENT or OPERATING privilege:
The POSIX subsystem must be installed (see “Installing POSIX”).
The POSIX information file may have to be modified (see "POSIX information file").
The name of the container file where the root file system is located must match the corresponding control parameter ROOTFSNAME in the POSIX information file.
During initial installation, the name of the new root file system is entered in the POSIX information file. Therefore, it is not necessary in this case to check for a match.
Write access to the container file of the root file system and all other file systems which are to be linked during POSIX startup must be possible (attribute ACCESS=*WRITE in the file catalog).
POSIX must be entered in the subsystem catalog.
When installing with IMON, it is entered automatically.
POSIX is started either automatically following successful initial installation, or explicitly by means of the BS2000 command
/START-SUBSYSTEM SUBSYSTEM-NAME=POSIX.
If the POSIX subsystem startup was successful, the following message appears on the screen:
POS4100: INIT: THE POSIX SUBSYSTEM IS READY.
If startup was unsuccessful, e.g. because the started initialization process could not be terminated, the cause is recorded in the log file of the init process $SYSROOT.SYSLOG.POSIX-BC.<version>.INIT.
Subsystem parameters
Two parameters are supported in the START-SUBSYSTEM command in order to force a consistency check and cleansing of the file system when POSIX starts up. The entries for these parameters are not case-sensitive, but they may not be abbreviated.
/START-SUBSYSTEM POSIX,SUBSYSTEM-PARAMETER='CHECK-SYSTEM-FS'The file systems below are checked with fsck before they are mounted and cleansed if required:
/ (root file system) /var /opt (only if present) /START-SUBSYSTEM POSIX,SUBSYSTEM-PARAMETER='CHECK-ALL-FS'All file systems are checked with fsck before they are mounted and cleansed if required.
Support of rc procedures
POSIX does not support the run level mechanism of native UNIX. However, similarly to UNIX, it is possible to define rc procedures which run automatically when POSIX is started and terminated. In the same way as for native UNIX, any rc procedures that are to be activated during startup must be stored in the /etc/rc2.d directory and procedures that are activated during termination must be stored in the /etc/rc0.d directory. The rc procedures are called one after the other in alphabetical order by the shell script /etc/rc2 or /etc/rc0 when POSIX is started or terminated. If the /etc/.trace.rc file exists, these calls are logged on the BS2000 console.
rc procedures for starting and terminating the following daemons are configured with POSIX-BC and POSIX-SH: shmd (shared memory daemon), syslogd (syslog daemon), fsmond (daemon for monitoring file system occupancy), rpcbind (daemon for RPC services), inetd (internet super daemon for network services), cron (daemon for the cron and at commands). Additional software products such as NFS install their own rc procedures for starting or terminating further daemons.
The maximum wait time for execution of the rc termination procedures during POSIX termination can be set by means of the new MAXTIMERC parameter in the information file (see "Description of control parameters"). If execution of the rc termination procedures has not been completed by the time this period has elapsed, depending on the value of the FORCEDTERM parameter POSIX termination will either be canceled or continued in abnormal mode.