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+ * Copyright 2018-2023,2024 Thomas E. Dickey *
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-<H1 class="no-header">tabs 1</H1>
+<H1 class="no-header">tabs 1 2024-04-20 ncurses 6.4 User commands</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>
+<STRONG><A HREF="tabs.1.html">tabs(1)</A></STRONG>
User commands <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
+ <STRONG>tabs</STRONG> - set terminal tab stops
</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
- <STRONG>tabs</STRONG> [<EM>options</EM>]] <EM>[tabstop-list]</EM>
+ <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
+ the terminfo <STRONG>clear_all_tabs</STRONG> and <STRONG>set_tab</STRONG> 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.,
<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
+ <STRONG>-V</STRONG> reports the version of <EM>ncurses</EM> which was used in this program, and
exits.
The <STRONG>tabs</STRONG> program processes a single list of tab stops. The last option
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.
+</PRE><H3><a name="h3-Predefined-Tab-Stops">Predefined Tab
Stops</a></H3><PRE>
+ POSIX defines several predefined lists of tab stops.
<STRONG>-a</STRONG> Assembler, IBM S/370, first format
+ 1,10,16,36,72
<STRONG>-a2</STRONG> Assembler, IBM S/370, second format
+ 1,10,16,40,72
<STRONG>-c</STRONG> COBOL, normal format
+ 1,8,12,16,20,55
<STRONG>-c2</STRONG> COBOL compact format
+ 1,6,10,14,49
<STRONG>-c3</STRONG> COBOL compact format extended
+ 1,6,10,14,18,22,26,30,34,38,42,46,50,54,58,62,67
<STRONG>-f</STRONG> FORTRAN
+ 1,7,11,15,19,23
<STRONG>-p</STRONG> PL/I
+ 1,5,9,13,17,21,25,29,33,37,41,45,49,53,57,61
<STRONG>-s</STRONG> SNOBOL
+ 1,10,55
<STRONG>-u</STRONG> UNIVAC 1100 Assembler
+ 1,12,20,44
+
+
+</PRE><H3><a name="h3-Margins">Margins</a></H3><PRE>
+ A few terminals expose a means of changing their left and right
+ margins. <STRONG>tabs</STRONG> supports this feature with an option.
+
+ <STRONG>+m</STRONG> <EM>margin</EM>
+ The effect depends on whether the terminal has the margin
+ capabilities:
+
+ <STRONG>o</STRONG> If the terminal provides the capability for setting the left
+ margin, <STRONG>tabs</STRONG> uses this, and adjusts the available tab stop
+ widths.
+
+ <STRONG>o</STRONG> If the terminal does not provide the margin capabilities, <STRONG>tabs</STRONG>
+ imitates their effect, putting tab stops at appropriate places
+ on each line. The terminal's left margin is not modified.
+
+ If the <EM>margin</EM> parameter is omitted, the default is 10. Use <STRONG>+m0</STRONG> to
+ reset the left margin, that is, to make it the left edge of the
+ terminal's display. Before setting a left margin, <STRONG>tabs</STRONG> resets the
+ margin to reduce problems that might arise from moving the cursor
+ to the left of the current left margin.
+
+ When setting or resetting the left margin, <STRONG>tabs</STRONG> may also reset the
+ right margin.
+
+
+</PRE><H2><a name="h2-FILES">FILES</a></H2><PRE>
+ <EM>/usr/share/tabset</EM>
+ tab stop initialization database
</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
+ IEEE Std 1003.1/The Open Group Base Specifications Issue 7
+ (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-
- margin. 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> this standard describes a <STRONG>+m</STRONG> option to set a terminal's left
+ margin. Very few of the entries in the terminal database provide
+ the <STRONG>set_left_margin</STRONG> (<STRONG>smgl</STRONG>) or <STRONG>set_left_margin_parm</STRONG> (<STRONG>smglp</STRONG>)
+ capabilities 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>.
+ <STRONG>o</STRONG> There is no counterpart in X/Open Curses Issue 7 for this utility,
+ unlike <STRONG><A HREF="tput.1.html">tput(1)</A></STRONG>.
- The <STRONG>-d</STRONG> (debug) and <STRONG>-n</STRONG> (no-op) options are extensions not provided by
- other implementations.
+ The <STRONG>-d</STRONG> (debug) and <STRONG>-n</STRONG> (no-op) options are <EM>ncurses</EM> 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.
+</PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
+ A <STRONG>tabs</STRONG> utility appeared in PWB/Unix 1.0 (1977). A reduced version
+ shipped in Seventh Edition Unix (early 1979) and in 3BSD (later the
+ same year); it supported a "-n" option to set the first tab stop at the
+ left margin. That option is not specified by POSIX.
- 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 <STRONG>tset</STRONG> (1982)
- and incorporated into <STRONG>tput</STRONG> uses the terminal database,
+ The PWB/Unix <STRONG>tabs</STRONG> utility returned in System III (1980), and used
+ built-in tables to support a half-dozen hardcopy terminal (printer)
+ types. It also had logic to support setting the left margin, as well
+ as a feature for copying the tab settings from a file.
- 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.
+ Versions of the program in later releases of AT&T Unix, such as SVr4,
+ added support for the terminal database, but retained the tables to
+ support the printers. By this time, System V <STRONG>tput</STRONG> had incorporated the
+ tab stop initialization feature of BSD's <STRONG>tset</STRONG> from 1982, but employed
+ the <EM>terminfo</EM> database to do so.
- 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
+ The <STRONG>+m</STRONG> option was documented in the POSIX Base Specifications Issue 5
+ (Unix98, 1997), then omitted in Issue 6 (Unix03, 2004) without express
+ motivation, though an introductory comment "and optionally adjusts the
+ margin" remains, overlooked in the removal. The <STRONG>tabs</STRONG> utility
+ documented in Issues 6 and later has no mechanism for setting margins.
+ The <STRONG>+m</STRONG> option in <EM>ncurses</EM> <STRONG>tabs</STRONG> differs from the SVr4 feature by using
+ terminal capabilities rather than built-in tables.
- no known historical version of tabs supports the capability of
- setting arbitrary tab stops.
+ POSIX documents no limit on the number of tab stops. Other
+ implementations impose one; the limit is 20 in PWB/Unix's <STRONG>tabs</STRONG> utility.
+ While some terminals may not accept an arbitrary number of tab stops,
+ <EM>ncurses</EM> <STRONG>tabs</STRONG> attempts to set tab stops up to the right margin if the
+ list thereof is sufficiently long.
- However, the <EM>Explicit</EM> <EM>Lists</EM> described in this manual page were
- implemented in PWB/Unix. Those provide the capability of setting
- abitrary tab stops.
+ The "Rationale" section of the Issue 6 <STRONG>tabs</STRONG> reference page details how
+ the committee considered redesigning the <STRONG>tabs</STRONG> and <STRONG>tput</STRONG> utilities,
+ without settling on an improved solution. It claims that
+ "no known historical version of <EM>tabs</EM> supports the capability of
+ setting arbitrary tab stops."
+
+ The feature described in subsection "Explicit Lists" above was
+ implemented in PWB/Unix, and permitted the setting of abitrary tab
+ stops nevertheless.
-</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
- <STRONG><A HREF="infocmp.1m.html">infocmp(1m)</A></STRONG>, <STRONG><A HREF="tset.1.html">tset(1)</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 20210522).
+</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
+ <STRONG><A HREF="infocmp.1m.html">infocmp(1m)</A></STRONG>, <STRONG><A HREF="tset.1.html">tset(1)</A></STRONG>, <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>
-
<STRONG><A HREF="tabs.1.html">tabs(1)</A></STRONG>
+
ncurses 6.4 2024-04-20 <STRONG><A HREF="tabs.1.html">tabs(1)</A></STRONG>
</PRE>
<div class="nav">
<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>
+<li><a href="#h3-Predefined-Tab-Stops">Predefined Tab Stops</a></li>
+<li><a href="#h3-Margins">Margins</a></li>
</ul>
</li>
+<li><a href="#h2-FILES">FILES</a></li>
<li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
+<li><a href="#h2-HISTORY">HISTORY</a></li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
</ul>
</div>
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