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NAME | DESCRIPTION | PORTABILITY | FILES | SEE ALSO | COLOPHON |
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term(7) Miscellaneous Information Manual term(7)
term - conventions for naming terminal types
The environment variable TERM should normally contain the type
name of the terminal, console or display-device type you are
using. This information is critical for all screen-oriented
programs, including your editor and mailer.
A default TERM value will be set on a per-line basis by either
/etc/inittab (e.g., System-V-like UNIXes) or /etc/ttys (BSD
UNIXes). This will nearly always suffice for workstation and
microcomputer consoles.
If you use a dialup line, the type of device attached to it may
vary. Older UNIX systems pre-set a very dumb terminal type like
“dumb” or “dialup” on dialup lines. Newer ones may pre-set
“vt100”, reflecting the prevalence of DEC VT100-compatible
terminals and personal-computer emulators.
Modern telnets pass your TERM environment variable from the local
side to the remote one. There can be problems if the remote
terminfo or termcap entry for your type is not compatible with
yours, but this situation is rare and can almost always be
avoided by explicitly exporting “vt100” (assuming you are in fact
using a VT100-superset console, terminal, or terminal emulator).
In any case, you are free to override the system TERM setting to
your taste in your shell profile. The @TSET@(1) utility may be
of assistance; you can give it a set of rules for deducing or
requesting a terminal type based on the tty device and baud rate.
Setting your own TERM value may also be useful if you have
created a custom entry incorporating options (such as visual bell
or reverse-video) which you wish to override the system default
type for your line.
Terminal type descriptions are stored as files of capability data
underneath @TERMINFO@. To browse a list of all terminal names
recognized by the system, do
@TOE@ | more
from your shell. These capability files are in a binary format
optimized for retrieval speed (unlike the old text-based termcap
format they replace); to examine an entry, you must use the
@INFOCMP@(1M) command. Invoke it as follows:
@INFOCMP@ entry_name
where entry_name is the name of the type you wish to examine (and
the name of its capability file the subdirectory of @TERMINFO@
named for its first letter). This command dumps a capability
file in the text format described by terminfo(5).
The first line of a terminfo(5) description gives the names by
which terminfo knows a terminal, separated by “|” (pipe-bar)
characters with the last name field terminated by a comma. The
first name field is the type's primary name, and is the one to
use when setting TERM. The last name field (if distinct from the
first) is actually a description of the terminal type (it may
contain blanks; the others must be single words). Name fields
between the first and last (if present) are aliases for the
terminal, usually historical names retained for compatibility.
There are some conventions for how to choose terminal primary
names that help keep them informative and unique. Here is a
step-by-step guide to naming terminals that also explains how to
parse them:
First, choose a root name. The root will consist of a lower-case
letter followed by up to seven lower-case letters or digits. You
need to avoid using punctuation characters in root names, because
they are used and interpreted as filenames and shell meta-
characters (such as !, $, *, ?, etc.) embedded in them may cause
odd and unhelpful behavior. The slash (/), or any other
character that may be interpreted by anyone's file system (\, $,
[, ]), is especially dangerous (terminfo is platform-independent,
and choosing names with special characters could someday make
life difficult for users of a future port). The dot (.)
character is relatively safe as long as there is at most one per
root name; some historical terminfo names use it.
The root name for a terminal or workstation console type should
almost always begin with a vendor prefix (such as hp for Hewlett-
Packard, wy for Wyse, or att for AT&T terminals), or a common
name of the terminal line (vt for the VT series of terminals from
DEC, or sun for Sun Microsystems workstation consoles, or regent
for the ADDS Regent series. You can list the terminfo tree to
see what prefixes are already in common use. The root name
prefix should be followed when appropriate by a model number;
thus vt100, hp2621, wy50.
The root name for a PC-Unix console type should be the OS name,
i.e., linux, bsdos, freebsd, netbsd. It should not be console or
any other generic that might cause confusion in a multi-platform
environment! If a model number follows, it should indicate
either the OS release level or the console driver release level.
The root name for a terminal emulator (assuming it does not fit
one of the standard ANSI or vt100 types) should be the program
name or a readily recognizable abbreviation of it (i.e.,
versaterm, ctrm).
Following the root name, you may add any reasonable number of
hyphen-separated feature suffixes.
2p Has two pages of memory. Likewise 4p, 8p, etc.
mc Magic-cookie. Some terminals (notably older Wyses) can only
support one attribute without magic-cookie lossage. Their
base entry is usually paired with another that has this
suffix and uses magic cookies to support multiple
attributes.
-am Enable auto-margin (right-margin wraparound).
-m Mono mode - suppress color support.
-na No arrow keys - termcap ignores arrow keys which are
actually there on the terminal, so the user can use the
arrow keys locally.
-nam No auto-margin - suppress am capability.
-nl No labels - suppress soft labels.
-nsl No status line - suppress status line.
-pp Has a printer port which is used.
-rv Terminal in reverse video mode (black on white).
-s Enable status line.
-vb Use visible bell (flash) rather than beep.
-w Wide; terminal is in 132-column mode.
Conventionally, if your terminal type is a variant intended to
specify a line height, that suffix should go first. So, for a
hypothetical FuBarCo model 2317 terminal in 30-line mode with
reverse video, best form would be fubar-30-rv (rather than, say,
“fubar-rv-30”).
Terminal types that are written not as standalone entries, but
rather as components to be plugged into other entries via use
capabilities, are distinguished by using embedded plus signs
rather than dashes.
Commands which use a terminal type to control display often
accept a -T option that accepts a terminal name argument. Such
programs should fall back on the TERM environment variable when
no -T option is specified.
For maximum compatibility with older System V UNIXes, names and
aliases should be unique within the first 14 characters.
@TERMINFO@/?/*
compiled terminal capability database
/etc/inittab
tty line initialization (AT&T-like UNIXes)
/etc/ttys
tty line initialization (BSD-like UNIXes)
curses(3X), terminfo(5), term(5).
This page is part of the ncurses (new curses) project.
Information about the project can be found at
⟨https://www.gnu.org/software/ncurses/ncurses.html⟩. If you have
a bug report for this manual page, send it to
[email protected]. This page was obtained from the
project's upstream Git mirror of the CVS repository
⟨https://github.com/mirror/ncurses.git⟩ on 2024-06-14. (At that
time, the date of the most recent commit that was found in the
repository was 2023-03-12.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
term(7)
Pages that refer to this page: terminfo(5)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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