User Guide

Ampex 1308911-02 v
DST/DIS Tape Drive UNIX Programmer’s Guide Addendum
Note:
To use pt functions, the function goes through the devscsi driver. Upon every system
reboot, devscsi permissions are reset to root access only. Therefore, to use the
passthru function, the devscsi permissions must be changed to give user read/write
access after every reboot.
Functions that use the pt interface must specify a file descriptor that provides a devscsi path
name. To obtain a devscsi file descriptor:
1. open() the tpsc device driver for mt operation.
2. Run dst_getptpathname() to get a devscsi path name (based on the tpsc file descriptor
that is currently open).
3. Close the tpsc file descriptor.
4. Open the devscsi device driver using the path name obtained in step 2. Use the file
descriptor returned by the open() call for the
*_pt function(s).