CPCMD(4,F) AIX Technical Reference CPCMD(4,F) ------------------------------------------------------------------------------- cpcmd PURPOSE Supports the IBM VM CP system interface. # include # include DESCRIPTION The AIX/370 system runs as a guest under VM. At times, it is desirable for programs to communicate through this interface. The device used to obtain this interface to VM is /dev/cpcmd. The cpcmd special file is unique to AIX/370. There is only one such device per system. Only the superuser can open this device. This avoids giving non-privileged AIX users the full privileges of the AIX/370 virtual machine within the realm of VM. Most I/O through this device is performed via ioctl commands describe below. It is possible, however, to write to the device a specific CP command. This command should be in ASCII, but otherwise in the format required by VM (for instance, all uppercase letters). There is one IOCTL operation available besides the standard IOCTYPE and IOCINFO commands. This is the CPCMD ioctl command. The CPCMD ioctl is of the form: ioctl (fd, CPCMD, arg) struct cpcmds *arg; The cpcmd structure is declared as follows: struct cpcmds { int inlen; int maxoutlen; char *inbuf; char *outbuf; int *outlen; }; The inbuf contains the command to be run, and the outbuf is to store the result returned by CP. This method allows the execution of each CP command to be atomic. ERROR CONDITIONS In addition to the errors listed in "ioctlx, ioctl, gtty, stty," "open, openx, creat," and "write, writex," system calls to this device can fail in the following circumstances: Processed November 7, 1990 CPCMD(4,F) 1 CPCMD(4,F) AIX Technical Reference CPCMD(4,F) EPERM Attempt to open the device by non-superuser. EINVAL The CP command is not valid. RELATED INFORMATION In this book: "ioctlx, ioctl, gtty, stty," "open, openx, creat," and "write, writex." The cpcmd command in AIX Operating System Commands Reference. Processed November 7, 1990 CPCMD(4,F) 2