System Administration Guide
Chapter 7, Connecting to other computers with UUCP

Configuring UUCP for 7-bit systems

Configuring UUCP for 7-bit systems

Most UUCP systems use 8 data bits, one stop bit, and no parity for communicating over serial links. However, some implementations use 7 data bits, one stop bit, and one parity bit. Parity may be even, odd, or ignored.

To permit outgoing UUCP connections to a 7-bit system, you must modify the Systems file entry for that system. Two special keywords are recognized: PEVEN and PODD. PEVEN means even parity is to be used; PODD means odd parity is to be used. If both are specified, no parity is used. For example:

7-bit even:

   remote Any ACU 2400 4253502 PEVEN -\r\d-ogin:-\K\d-ogin:-\K\d-ogin: uusys
7-bit odd:
   remote Any ACU 2400 4253502 PODD -\r\d-ogin:-\K\d-ogin:-\K\d-ogin: uusys
7-bit none:
   remote Any ACU 2400 4253502 PEVEN PODD -\r\d-ogin:-\K\d-ogin:-\K\d-ogin: uusys
To receive incoming calls from a 7-bit system, specify an appropriate /etc/gettydefs entry in the /etc/inittab entry for the modem port. As no 7-bit configurations are provided, you will need to add one. Be sure to leave blank lines above and below the new entry. For full details of a gettydefs entry, see the gettydefs(F) manual page.

The /etc/gettydefs file recognizes three special keywords:

PARENB
use even parity

PARODD
use odd parity

IGNPAR
ignore parity
For example, assuming an incoming call is expected on tty1A, the following changes should be made to /etc/inittab and /etc/gettydefs:

7-bit even:

/etc/inittab

Se1A:2:respawn:/etc/getty -t60 tty1A 24E

/etc/gettydefs

24E#B2400HUPCL#B2400CS7PARENBHUPCLTAB3ECHOEIXANY#\r\n@!login:#24E

7-bit odd:

/etc/inittab

Se1A:2:respawn:/etc/getty -t60 tty1A 240

/etc/gettydefs

24O#B2400HUPCL#B2400CS7PARODDHUPCLTAB3ECHOEIXANY#\r\n@!login:#24O

7-bit none:

/etc/inittab

Se1A:2:respawn:/etc/getty -t60 tty1A 2DN

/etc/gettydefs

24N#B2400HUPCL#B2400CS7IGNPARHUPCLTAB3ECHOEIXANY#\r\n@!login:#24N

For more information about parity settings, see the stty(C) manual page.