Sunday, March 31, 2013

Using tip for Serial Terminal Access

The tip command can be used to allow one Unix workstation to act as a serial terminal for another Unix system. The following must be in place to allow this to work between two Sun systems:

  • The system to be observed should be halted. If a keyboard needs to be removed from the system, the system should be powered off. (Some older models will blow a keyboard fuse if the keyboard is removed while the system is powered up.)
  • The /etc/remote file on the observing machine needs to have the hardwire line pointing to the correct serial port.
    • By default, the file points at port b. In this case, the line should look like:
    • If serial port a is to be used, change the line to look like:
  • A null modem cable should be run between serial port a on the system that is under observation and the serial port configured in the /etc/remote file's hardwire line on the observing system. (A null modem cable interchanges wires 2 and 3 on one end.)

On the observer system type "tip hardwire" in a window. (It is best to use a windowed environment so that control of the system can be regained in case of a session hang.) A "connected" message should be echoed to the window. If not, use admintool or another utility to see if the serial port is already in use.

A tip session should not be closed by killing the process, the shell, or rebooting the observer machine. In these cases a /var/spool/locks/LCK file may not be cleaned up properly, which may prevent further tip sessions.

Some common tip commands are:

  • ~. (end session)
  • ~# (break--same as STOP-A)
  • ~? (list all tip commands)
(Other commands may be found on the tip man page.)

The system to be observed/controlled can be powered up. If the diag-switch? PROM environment variable is set to true, hardware diagnostic data will be displayed to the tip window. (See the Hardware Diagnostics page for further information.)

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