The @TABS@ program clears and sets tab-stops on the terminal. This
uses the terminfo clear_all_tabs and set_tab capabilities. If either
is absent, @TABS@ is unable to clear/set tab-stops. The terminal
should be configured to use hard tabs, e.g.,
Like @CLEAR@(1), @TABS@ writes to the standard output. You can
redirect the standard output to a file (which prevents @TABS@ from
actually changing the tabstops), and later cat the file to the
screen, setting tabstops at that point.
These are hardware tabs, which cannot be queried rapidly by
applications running in the terminal, if at all. Curses and other
full-screen applications may use hardware tabs in optimizing their
output to the terminal. If the hardware tabstops differ from the
information in the terminal database, the result is unpredictable.
Before running curses programs, you should either reset tab-stops to
the standard interval
or use the @RESET@ program, since the normal initialization sequences
do not ensure that tab-stops are reset.
Tell @TABS@ which terminal type to use. If this option is not
given, @TABS@ will use the $TERM environment variable. If that
is not set, it will use the ansi+tabs entry.
-d The debugging option shows a ruler line, followed by two data
lines. The first data line shows the expected tab-stops marked
with asterisks. The second data line shows the actual tab-
stops, marked with asterisks.
-n This option tells @TABS@ to check the options and run any
debugging option, but not to modify the terminal settings.
-V reports the version of ncurses which was used in this program,
The @TABS@ program processes a single list of tab stops. The last
option to be processed which defines a list is the one that
determines the list to be processed.
Use a single number as an option, e.g., “-5” to set tabs at the given
interval (in this case 1, 6, 11, 16, 21, etc.). Tabs are repeated up
to the right margin of the screen.
Use “-0” to clear all tabs.
Use “-8” to set tabs to the standard interval.
An explicit list can be defined after the options (this does not use
a “-”). The values in the list must be in increasing numeric order,
and greater than zero. They are separated by a comma or a blank, for
tabs 1 6 11 16 21
Use a “+” to treat a number as an increment relative to the previous
which is equivalent to the 1,6,11,16,21 example.
X/Open defines several predefined lists of tab stops.
-a Assembler, IBM S/370, first format
-a2 Assembler, IBM S/370, second format
-c COBOL, normal format
-c2 COBOL compact format
-c3 COBOL compact format extended
-u UNIVAC 1100 Assembler
IEEE Std 1003.1/The Open Group Base Specifications Issue 7
(POSIX.1-2008) describes a tabs utility. However
· This standard describes a +m option, to set a terminal's left-
margin. Very few of the entries in the terminal database provide
the smgl (set_left_margin) or smglp (set_left_margin_parm)
capability needed to support the feature.
· There is no counterpart in X/Open Curses Issue 7 for this
utility, unlike @TPUT@(1).
The -d (debug) and -n (no-op) options are extensions not provided by
A tabs utility appeared in PWB/Unix 1.0 (1977). There was a reduced
version of the tabs utility in Unix 7th edition and in 3BSD (1979).
The latter supported a single “-n” option (to cause the first tab
stop to be set on the left margin). That option is not documented by
The PWB/Unix tabs utility, which was included in System III (1980),
used built-in tables rather than the terminal database, to support a
half-dozen terminal types. It also had built-in logic to support the
left-margin, as well as a feature for copying the tab settings from a
Later versions of Unix, e.g., SVr4, added support for the terminal
database, but kept the tables, as a fallback. In an earlier
development effort, the tab-stop initialization provided by tset
(1982) and incorporated into tput uses the terminal database,
POSIX documents no limits on the number of tab stops. Documentation
for other implementations states that there is a limit on the number
of tab stops (e.g., 20 in PWB/Unix's tabs utility). While some
terminals may not accept an arbitrary number of tab stops, this
implementation will attempt to set tab stops up to the right margin
of the screen, if the given list happens to be that long.
The Rationale section of the POSIX documentation goes into some
detail about the ways the committee considered redesigning the tabs
and tput utilities, without proposing an improved solution. It
no known historical version of tabs supports the capability of
setting arbitrary tab stops.
However, the Explicit Lists described in this manual page were
implemented in PWB/Unix. Those provide the capability of setting
abitrary tab stops.
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@example.com. This page was obtained from the
project's upstream Git mirror of the CVS repository
⟨git://ncurses.scripts.mit.edu/ncurses.git⟩ on 2020-05-27. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2020-05-24.) 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 firstname.lastname@example.org