Preventing respawns with inittab

6.10 LPAR mode z/VM guest

Typical inittab entries differ, depending on the type of terminal and whether the availability of the terminal is assured.

To use ttyrun with an entry for mingetty, change the entry to this form:

<id>:2345:respawn:/sbin/ttyrun <dev> /sbin/mingetty --noclear %t

To use ttyrun with an entry for agetty, change the entry to this form:

<id>:2345:respawn:/sbin/ttyrun <dev> /sbin/agetty -L 9600 %t <term>

where:

<id>

is a unique identifier for the entry in the inittab file.

<dev>

specifies the device node of the terminal, omitting the leading /dev/. For example, instead of specifying /dev/sclp_line0, specify sclp_line0.

<term>

specifies the terminal name. The terminal name indicates the capabilities of the terminal device. Examples for terminal names are linux, dumb, xterm, or vt220.

With mingetty, you must explicitly export the TERM environment variable with the terminal name

mingetty example:

# export TERM=linux

%t

is a variable that the ttyrun program resolves to the device node that is specified for <dev>.

By default, ttyrun runs quietly. Use the verbose option, -V, to obtain syslog messages, for example, if a terminal device is not available.

Example

To enable terminal devices hvc0 through hvc3 for user logins with agetty and to take into account that the terminals might not be operational, specify, for example:

h0:2345:respawn:/sbin/ttyrun -V hvc0 /sbin/agetty -L 9600 %t linux
h1:2345:respawn:/sbin/ttyrun hvc1 /sbin/agetty -L 9600 %t linux
h2:2345:respawn:/sbin/ttyrun hvc2 /sbin/agetty -L 9600 %t linux
h3:2345:respawn:/sbin/ttyrun hvc3 /sbin/agetty -L 9600 %t linux

These terminal devices are operational only in a z/VM® environment. In addition, they depend on the hvc_iucv= kernel parameter. The verbose option, -V, in the first line causes a syslog entry if the hvc0 terminal device is not available. The other lines omit this option, so no syslog entries are created if any of the other terminal devices are unavailable.