Talking Serially: Terminal Configuration in Linux

/etc/inittab

Linux's agetty does not use the ttytype or gettydefs files. All terminal configuration takes place in the inittab with agetty obtaining all of its information from the process field.

Most Linux distributions come with up to two more getty programs: getty_ps, and mgetty, which behave differently. agetty is the simplest of the three, and is used by default in the Slackware distribution.

Typical terminal entries in Linux inittab files look like this:

s2:45:respawn:/sbin/agetty 19200 ttyS1 vt100

In the process field, the arguments to agetty are as follows:

• 19200 specifies the bit rate to be used with the port. This can be a comma-spearated list of one or more bit rates for agetty to cycle through when it receives a BREAK character.
• ttyS1 is the port to monitor.
• vt100 is the terminal type, which will be used for the TERM environment variable.

After modifying the inittab, issue the command telinit q to activate it.