Provides a process with an I/O channel so input/output operations can be performed on a device, or establishes a logical link with a remote node on a network. On Alpha and Integrity server systems, this service accepts 64- bit addresses. Format SYS$ASSIGN devnam ,chan ,[acmode] ,[mbxnam] ,[flags] C Prototype int sys$assign (void *devnam, unsigned short int *chan, unsigned int acmode, void *mbxnam,...);
1 – Arguments
devnam OpenVMS usage:device_name type: character-coded text string access: read only mechanism: by 32- or 64-bit descriptor-fixed-length string descriptor Name of the device to which $ASSIGN is to assign a channel. The devnam argument is the 32- or 64-bit address of a character string descriptor pointing to the device name string. If the device name contains a double colon (::), the system assigns a channel to the first available network device (NET:) and performs an access function on the network. chan OpenVMS usage:channel type: word (unsigned) access: write only mechanism: by 32- or 64-bit reference Number of the channel that is assigned. The chan argument is the 32- or 64-bit address of a word into which $ASSIGN writes the channel number. acmode OpenVMS usage:access_mode type: longword (unsigned) access: read only mechanism: by value Access mode to be associated with the channel. The acmode argument specifies the access mode. The $PSLDEF macro defines the following symbols for the four access modes: Symbol Access Mode Numeric Value PSL$C_KERNEL Kernel 0 PSL$C_EXEC Executive 1 PSL$C_SUPER Supervisor 2 PSL$C_USER User 3 The specified access mode and the access mode of the caller are compared. The less privileged (but the higher numeric valued) of the two access modes becomes the access mode associated with the assigned channel. I/O operations on the channel can be performed only from equal and more privileged access modes. For more information, see the section on access modes in the HP OpenVMS Programming Concepts Manual. mbxnam OpenVMS usage:device_name type: character-coded text string access: read only mechanism: by 32- or 64-bit descriptor-fixed-length string descriptor Logical name of the mailbox to be associated with the device. The mbxnam argument is the 32- or 64-bit address of a character string descriptor pointing to the logical name string. If you specify mbxnam as 0, no mailbox is associated with the device. This is the default. You must specify the mbxnam argument when performing a nontransparent, task-to-task, network operation. Only the owner of a device can associate a mailbox with the device; the owner of a device is the process that has allocated the device, whether implicitly or explicitly. Only one mailbox can be associated with a device at any one time. For unshareable, nonspooled devices, an implicit $ALLOCATE is done. This requires read, write, or control access to the device. A mailbox cannot be associated with a device if the device has foreign (DEV$M_FOR) or shareable (DEV$M_SHR) characteristics. A mailbox is disassociated from a device when the channel that associated it is deassigned. If a mailbox is associated with a device, the device driver can send status information to the mailbox. For example, if the device is a terminal, this information might indicate dialup, hangup, or the reception of unsolicited input; if the device is a network device, it might indicate that the network is connected or perhaps that the line is down. For details on the nature and format of the information returned to the mailbox, see the HP OpenVMS I/O User's Reference Manual. flags OpenVMS usage:mask_longword type: longword (unsigned) access: read only mechanism: by value An optional device-specific argument. The flags argument is a longword bit mask. For more information on the applicability of the flags argument for a particular device, see the HP OpenVMS I/O User's Reference Manual.