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<H1 class="no-header">tabs 1</H1>
<PRE>
<STRONG><A HREF="tabs.1.html">tabs(1)</A></STRONG> General Commands Manual <STRONG><A HREF="tabs.1.html">tabs(1)</A></STRONG>
</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
<STRONG>tabs</STRONG> - set tabs on a terminal
</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
<STRONG>tabs</STRONG> [<EM>options</EM>]] <EM>[tabstop-list]</EM>
</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
The <STRONG>tabs</STRONG> program clears and sets tab-stops on the terminal. This uses
the terminfo <EM>clear</EM><STRONG>_</STRONG><EM>all</EM><STRONG>_</STRONG><EM>tabs</EM> and <EM>set</EM><STRONG>_</STRONG><EM>tab</EM> capabilities. If either is
absent, <STRONG>tabs</STRONG> is unable to clear/set tab-stops. The terminal should be
configured to use hard tabs, e.g.,
stty tab0
Like <STRONG><A HREF="clear.1.html">clear(1)</A></STRONG>, <STRONG>tabs</STRONG> writes to the standard output. You can redirect
the standard output to a file (which prevents <STRONG>tabs</STRONG> from actually chang-
ing the tabstops), and later <STRONG>cat</STRONG> the file to the screen, setting tab-
stops at that point.
These are hardware tabs, which cannot be queried rapidly by applica-
tions 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
tabs -8
or use the <STRONG>reset</STRONG> program, since the normal initialization sequences do
not ensure that tab-stops are reset.
</PRE><H2><a name="h2-OPTIONS">OPTIONS</a></H2><PRE>
</PRE><H3><a name="h3-General-Options">General Options</a></H3><PRE>
<STRONG>-T</STRONG><EM>name</EM>
Tell <STRONG>tabs</STRONG> which terminal type to use. If this option is not
given, <STRONG>tabs</STRONG> will use the <STRONG>$TERM</STRONG> environment variable. If that is
not set, it will use the <EM>ansi+tabs</EM> entry.
<STRONG>-d</STRONG> 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.
<STRONG>-n</STRONG> This option tells <STRONG>tabs</STRONG> to check the options and run any debugging
option, but not to modify the terminal settings.
<STRONG>-V</STRONG> reports the version of ncurses which was used in this program, and
exits.
The <STRONG>tabs</STRONG> 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.
</PRE><H3><a name="h3-Implicit-Lists">Implicit Lists</a></H3><PRE>
Use a single number as an option, e.g., "<STRONG>-5</STRONG>" 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 "<STRONG>-0</STRONG>" to clear all tabs.
Use "<STRONG>-8</STRONG>" to set tabs to the standard interval.
</PRE><H3><a name="h3-Explicit-Lists">Explicit Lists</a></H3><PRE>
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 exam-
ple,
tabs 1,6,11,16,21
tabs 1 6 11 16 21
Use a "+" to treat a number as an increment relative to the previous
value, e.g.,
tabs 1,+5,+5,+5,+5
which is equivalent to the 1,6,11,16,21 example.
</PRE><H3><a name="h3-Predefined-Tab-Stops">Predefined Tab-Stops</a></H3><PRE>
X/Open defines several predefined lists of tab stops.
<STRONG>-a</STRONG> Assembler, IBM S/370, first format
<STRONG>-a2</STRONG> Assembler, IBM S/370, second format
<STRONG>-c</STRONG> COBOL, normal format
<STRONG>-c2</STRONG> COBOL compact format
<STRONG>-c3</STRONG> COBOL compact format extended
<STRONG>-f</STRONG> FORTRAN
<STRONG>-p</STRONG> PL/I
<STRONG>-s</STRONG> SNOBOL
<STRONG>-u</STRONG> UNIVAC 1100 Assembler
</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
<EM>IEEE</EM> <EM>Std</EM> <EM>1003.1/The</EM> <EM>Open</EM> <EM>Group</EM> <EM>Base</EM> <EM>Specifications</EM> <EM>Issue</EM> <EM>7</EM>
(POSIX.1-2008) describes a <STRONG>tabs</STRONG> utility. However
<STRONG>o</STRONG> This standard describes a <STRONG>+m</STRONG> option, to set a terminal's left-mar-
gin. Very few of the entries in the terminal database provide the
<STRONG>smgl</STRONG> (<STRONG>set_left_margin</STRONG>) or <STRONG>smglp</STRONG> (<STRONG>set_left_margin_parm</STRONG>) capability
needed to support the feature.
<STRONG>o</STRONG> There is no counterpart in X/Open Curses Issue 7 for this utility,
unlike <STRONG>tput(1)</STRONG>.
The <STRONG>-d</STRONG> (debug) and <STRONG>-n</STRONG> (no-op) options are extensions not provided by
other implementations.
A <STRONG>tabs</STRONG> utility appeared in PWB/Unix 1.0 (1977). There was a reduced
version of the <STRONG>tabs</STRONG> 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 POSIX.
The PWB/Unix <STRONG>tabs</STRONG> 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
file.
Later versions of Unix, e.g., SVr4, added support for the terminal
database, but kept the tables, as a fallback. In an earlier develop-
ment effort, the tab-stop initialization provided by <STRONG>tset</STRONG> (1982) and
incorporated into <STRONG>tput</STRONG> 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 <STRONG>tabs</STRONG> 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 <EM>Rationale</EM> section of the POSIX documentation goes into some detail
about the ways the committee considered redesigning the <STRONG>tabs</STRONG> and <STRONG>tput</STRONG>
utilities, without proposing an improved solution. It comments that
no known historical version of tabs supports the capability of
setting arbitrary tab stops.
However, the <EM>Explicit</EM> <EM>Lists</EM> described in this manual page were imple-
mented in PWB/Unix. Those provide the capability of setting abitrary
tab stops.
</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
<STRONG><A HREF="tset.1.html">tset(1)</A></STRONG>, <STRONG><A HREF="infocmp.1m.html">infocmp(1m)</A></STRONG>, <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>.
This describes <STRONG>ncurses</STRONG> version 6.2 (patch 20200212).
<STRONG><A HREF="tabs.1.html">tabs(1)</A></STRONG>
</PRE>
<div class="nav">
<ul>
<li><a href="#h2-NAME">NAME</a></li>
<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
<li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
<li><a href="#h2-OPTIONS">OPTIONS</a>
<ul>
<li><a href="#h3-General-Options">General Options</a></li>
<li><a href="#h3-Implicit-Lists">Implicit Lists</a></li>
<li><a href="#h3-Explicit-Lists">Explicit Lists</a></li>
<li><a href="#h3-Predefined-Tab-Stops">Predefined Tab-Stops</a></li>
</ul>
</li>
<li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
</ul>
</div>
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