GETTYTAB(5) | File Formats Manual | GETTYTAB(5)

# NAME

`gettytab` — terminal configuration database

# DESCRIPTION

The `gettytab` file is a simplified version of the termcap(5) database used to describe terminal lines. The initial terminal login process getty(8) accesses the `gettytab` file each time it starts, allowing simpler reconfiguration of terminal characteristics. Each entry in the database is used to describe one class of terminals.

There is a default terminal class, default, that is used to set global defaults for all other classes. (That is, the default entry is read, then the entry for the class required is used to override particular settings.)

# CAPABILITIES

Refer to termcap(5) for a description of the file layout. The default column below lists defaults obtained if there is no entry in the table obtained, nor one in the special default table.

Name | Type | Default | Description
ap | bool | false | Terminal uses any parity.
bk | str | 0377 | Alternative end-of-line character (input break).
c0 | num | unused | TTY control flags to write messages.
c1 | num | unused | TTY control flags to read login name.
c2 | num | unused | TTY control flags to leave terminal as.
ce | bool | false | Use CRT erase algorithm.
ck | bool | false | Use CRT kill algorithm.
cl | str | `NULL` | Screen clear sequence.
co | bool | false | Console; add ‘`\n`’ after login prompt.
ds | str | ‘`^Y`’ | Delayed suspend character.
dx | bool | false | Set `DECCTLQ`.
ec | bool | false | Leave echo OFF.
ep | bool | false | Terminal uses even parity.
er | str | ‘`^?`’ | Erase character.
et | str | ‘`^D`’ | End of text (`EOF`) character.
ev | str | `NULL` | Initial environment.
fl | str | ‘`^O`’ | Output flush character.
hc | bool | false | Do not hangup line on last close.
hn | str | hostname | Hostname.
ht | bool | false | Terminal has real tabs.
i0 | num | unused | TTY input flags to write messages.
i1 | num | unused | TTY input flags to read login name.
i2 | num | unused | TTY input flags to leave terminal as.
ig | bool | false | Ignore garbage characters in login name.
im | str | `NULL` | Initial (banner) message.
in | str | ‘`^C`’ | Interrupt character.
is | num | unused | Input speed.
kl | str | ‘`^U`’ | Kill character.
l0 | num | unused | TTY local flags to write messages.
l1 | num | unused | TTY local flags to read login name.
l2 | num | unused | TTY local flags to leave terminal as.
lc | bool | false | Terminal has lower case.
lm | str | login: | Login prompt.
ln | str | ‘`^V`’ | ``Literal next'' character.
lo | str | /usr/bin/login | Program to execute when name obtained.
mb | bool | false | Do flow control based on carrier.
nl | bool | false | Terminal has (or might have) a newline character.
np | bool | false | Terminal uses no parity (i.e., 8-bit characters).
nx | str | default | Next table (for auto speed selection).
o0 | num | unused | TTY output flags to write messages.
o1 | num | unused | TTY output flags to read login name.
o2 | num | unused | TTY output flags to leave terminal as.
op | bool | false | Terminal uses odd parity.
os | num | unused | Output speed.
pc | str | ‘`\0`’ | Pad character.
pe | bool | false | Use printer (hard copy) erase algorithm.
pf | num | 0 | Delay between first prompt and following flush (seconds).
ps | bool | false | Line connected to a MICOM port selector.
qu | str | ‘`^\`’ | Quit character.
rp | str | ‘`^R`’ | Line retype character.
rw | bool | false | Do not use raw for input, use cbreak.
sp | num | unused | Line speed (input and output).
su | str | ‘`^Z`’ | Suspend character.
tc | str | none | Table continuation.
to | num | 0 | Timeout (seconds).
tt | str | `NULL` | Terminal type (for environment).
ub | bool | false | Do unbuffered output (of prompts etc).
we | str | ‘`^W`’ | Word erase character.
xc | bool | false | Do not echo control characters as ‘`^X`’.
xf | str | ‘`^S`’ | `XOFF` (stop output) character.
xn | str | ‘`^Q`’ | `XON` (start output) character.

The following capabilities are no longer supported by getty(8):

bd | num | 0 | Backspace delay.
cb | bool | false | Use CRT backspace mode.
cd | num | 0 | Carriage-return delay.
f0 | num | unused | TTY mode flags to write messages.
f1 | num | unused | TTY mode flags to read login name.
f2 | num | unused | TTY mode flags to leave terminal as.
fd | num | 0 | Form-feed (vertical motion) delay.
nd | num | 0 | Newline (line-feed) delay.
uc | bool | false | Terminal is known upper case only.

If no line speed is specified, speed will not be altered from that which prevails when getty(8) is entered. Specifying an input or output speed will override line speed for stated direction only.

Terminal modes to be used for the output of the message and for input of the login name, and to leave the terminal set as upon completion, are derived from the boolean flags specified. If the derivation should prove inadequate, any (or all) of these three may be overridden with one of the c0, c1, c2, i0, i1, i2, l0, l1, l2, o0, o1, or o2 numeric specifications, which can be used to specify (usually in octal, with a leading ‘`0`’) the exact values of the flags. These flags correspond to the termios c_cflag, c_iflag, c_lflag, and c_oflag fields, respectively. Each of these sets must be completely specified to be effective.

Should getty(8) receive a null character (presumed to indicate a line break) it will restart using the table indicated by the nx entry. If there is none, it will re-use its original table.

Delays are specified in milliseconds; the nearest possible delay available in the TTY driver will be used. Should greater certainty be desired, delays with values 0, 1, 2, and 3 are interpreted as choosing that particular delay algorithm from the driver.

The cl screen clear string may be preceded by a (decimal) number of milliseconds of delay required (a la termcap(5)). This delay is simulated by repeated use of the pad character pc.

The initial message and login message (im and lm) may include any of the following character sequences, which expand to information about the environment in which getty(8) is running:

%d
  The current date.
%h
  The hostname of the machine, which is normally obtained from the system using gethostname(3), but may also be overridden by the hn table entry.
%t
  The TTY name.
%m, %r, %s, %v
  The type of machine, release of the operating system, name of the operating system, and version of the kernel, respectively, as returned by uname(3).
%%
  A ‘`%`’ character.

When getty(8) executes the login process given in the lo string (usually /usr/bin/login), it will have set the environment to include the terminal type, as indicated by the tt string (if it exists). The ev string can be used to enter additional data into the environment. It is a list of comma-separated strings, each of which will presumably be of the form name=value.

If a non-zero timeout is specified with to, then getty(8) will exit within the indicated number of seconds, either having received a login name and passed control to login(1), or having received an alarm signal and exited. This may be useful to hangup dial in lines.

Output from getty(8) is even parity unless op or np is specified. The op string may be specified with ap to allow any parity on input, but generate odd parity output. Note: this only applies while getty(8) is being run; terminal driver limitations prevent a more complete implementation. getty(8) does not check parity of input characters in `RAW` mode.

If a pp string is specified and a PPP link bring-up sequence is recognized, getty(8) will invoke the program referenced by the pp option. This can be used to handle incoming PPP calls.

# FILES

/etc/gettytab
  Default location of the database file.

# SEE ALSO

login(1), gethostname(3), uname(3), termcap(5), getty(8)

# HISTORY

The `gettytab` file format appeared in 4.2BSD.

# BUGS

The special characters (erase, kill, etc.) are reset to system defaults by login(1).

The delay stuff is a real crock. Apart from its general lack of flexibility, some of the delay algorithms are not implemented. The terminal driver should support sane delay settings.

The termcap(5) format is horrid; something more rational should have been chosen.

May 27, 2017 | Debian