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30 * @Id: tabs.1,v 1.51 2023/12/17 00:13:57 tom Exp @
31 * https://minnie.tuhs.org/cgi-bin/utree.pl?file=PWB1/sys/source/s2/\
33 * https://minnie.tuhs.org/cgi-bin/utree.pl?file=V7/usr/src/cmd/tabs.c
34 * https://minnie.tuhs.org/cgi-bin/utree.pl?file=3BSD/usr/src/cmd/\
36 * https://minnie.tuhs.org/cgi-bin/utree.pl?file=SysVR4/cmd/tabs/tabs.c
37 * https://pubs.opengroup.org/onlinepubs/009604499/utilities/tabs.html
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44 <TITLE>tabs 1 2023-12-16 ncurses 6.4 User commands</TITLE>
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49 <H1 class="no-header">tabs 1 2023-12-16 ncurses 6.4 User commands</H1>
51 <STRONG><A HREF="tabs.1.html">tabs(1)</A></STRONG> User commands <STRONG><A HREF="tabs.1.html">tabs(1)</A></STRONG>
56 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
57 <STRONG>tabs</STRONG> - set terminal tab stops
60 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
61 <STRONG>tabs</STRONG> [<EM>options</EM>] [<EM>tabstop-list</EM>]
64 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
65 The <STRONG>tabs</STRONG> program clears and sets tab-stops on the terminal. This uses
66 the terminfo <STRONG>clear_all_tabs</STRONG> and <STRONG>set_tab</STRONG> capabilities. If either is
67 absent, <STRONG>tabs</STRONG> is unable to clear/set tab-stops. The terminal should be
68 configured to use hard tabs, e.g.,
72 Like <STRONG><A HREF="clear.1.html">clear(1)</A></STRONG>, <STRONG>tabs</STRONG> writes to the standard output. You can redirect
73 the standard output to a file (which prevents <STRONG>tabs</STRONG> from actually
74 changing the tabstops), and later <STRONG>cat</STRONG> the file to the screen, setting
75 tabstops at that point.
77 These are hardware tabs, which cannot be queried rapidly by
78 applications running in the terminal, if at all. Curses and other
79 full-screen applications may use hardware tabs in optimizing their
80 output to the terminal. If the hardware tabstops differ from the
81 information in the terminal database, the result is unpredictable.
82 Before running curses programs, you should either reset tab-stops to
87 or use the <STRONG>reset</STRONG> program, since the normal initialization sequences do
88 not ensure that tab-stops are reset.
91 </PRE><H2><a name="h2-OPTIONS">OPTIONS</a></H2><PRE>
93 </PRE><H3><a name="h3-General-Options">General Options</a></H3><PRE>
94 <STRONG>-T</STRONG><EM>name</EM>
95 Tell <STRONG>tabs</STRONG> which terminal type to use. If this option is not
96 given, <STRONG>tabs</STRONG> will use the <STRONG>$TERM</STRONG> environment variable. If that is
97 not set, it will use the <EM>ansi+tabs</EM> entry.
99 <STRONG>-d</STRONG> The debugging option shows a ruler line, followed by two data
100 lines. The first data line shows the expected tab-stops marked
101 with asterisks. The second data line shows the actual tab-stops,
102 marked with asterisks.
104 <STRONG>-n</STRONG> This option tells <STRONG>tabs</STRONG> to check the options and run any debugging
105 option, but not to modify the terminal settings.
107 <STRONG>-V</STRONG> reports the version of <EM>ncurses</EM> which was used in this program, and
110 The <STRONG>tabs</STRONG> program processes a single list of tab stops. The last option
111 to be processed which defines a list is the one that determines the
112 list to be processed.
115 </PRE><H3><a name="h3-Implicit-Lists">Implicit Lists</a></H3><PRE>
116 Use a single number as an option, e.g., "<STRONG>-5</STRONG>" to set tabs at the given
117 interval (in this case 1, 6, 11, 16, 21, etc.). Tabs are repeated up
118 to the right margin of the screen.
120 Use "<STRONG>-0</STRONG>" to clear all tabs.
122 Use "<STRONG>-8</STRONG>" to set tabs to the standard interval.
125 </PRE><H3><a name="h3-Explicit-Lists">Explicit Lists</a></H3><PRE>
126 An explicit list can be defined after the options (this does not use a
127 "-"). The values in the list must be in increasing numeric order, and
128 greater than zero. They are separated by a comma or a blank, for
134 Use a "+" to treat a number as an increment relative to the previous
139 which is equivalent to the 1,6,11,16,21 example.
142 </PRE><H3><a name="h3-Predefined-Tab-Stops">Predefined Tab-Stops</a></H3><PRE>
143 POSIX defines several predefined lists of tab stops.
145 <STRONG>-a</STRONG> Assembler, IBM S/370, first format
148 <STRONG>-a2</STRONG> Assembler, IBM S/370, second format
151 <STRONG>-c</STRONG> COBOL, normal format
154 <STRONG>-c2</STRONG> COBOL compact format
157 <STRONG>-c3</STRONG> COBOL compact format extended
158 1,6,10,14,18,22,26,30,34,38,42,46,50,54,58,62,67
160 <STRONG>-f</STRONG> FORTRAN
163 <STRONG>-p</STRONG> PL/I
164 1,5,9,13,17,21,25,29,33,37,41,45,49,53,57,61
166 <STRONG>-s</STRONG> SNOBOL
169 <STRONG>-u</STRONG> UNIVAC 1100 Assembler
173 </PRE><H3><a name="h3-Margins">Margins</a></H3><PRE>
174 A few terminals provide the capability for changing their left/right
175 margins. The tabs program has an option to use this feature:
177 <STRONG>+m</STRONG> <EM>margin</EM>
178 The effect depends on whether the terminal has the margin
181 <STRONG>o</STRONG> If the terminal provides the capability for setting the left
182 margin, tabs uses this, and adjusts the available width for
185 <STRONG>o</STRONG> If the terminal does not provide the margin capabilities, tabs
186 imitates the effect, putting the tab stops at the appropriate
187 place on each line. The terminal's left-margin is not
190 If the <EM>margin</EM> parameter is omitted, the default is 10. Use <STRONG>+m0</STRONG> to
191 reset the left margin, i.e., to the left edge of the terminal's
192 display. Before setting a left-margin, tabs resets the margin to
193 reduce problems which might arise on moving the cursor before the
196 When setting or resetting the left-margin, tabs may reset the right-
200 </PRE><H2><a name="h2-FILES">FILES</a></H2><PRE>
201 <EM>/usr/share/tabset</EM>
202 tab stop initialization database
205 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
206 <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>
207 (POSIX.1-2008) describes a <STRONG>tabs</STRONG> utility. However
209 <STRONG>o</STRONG> This standard describes a <STRONG>+m</STRONG> option, to set a terminal's left-
210 margin. Very few of the entries in the terminal database provide
211 the <STRONG>smgl</STRONG> (<STRONG>set_left_margin</STRONG>) or <STRONG>smglp</STRONG> (<STRONG>set_left_margin_parm</STRONG>)
212 capability needed to support the feature.
214 <STRONG>o</STRONG> There is no counterpart in X/Open Curses Issue 7 for this utility,
215 unlike <STRONG><A HREF="tput.1.html">tput(1)</A></STRONG>.
217 The <STRONG>-d</STRONG> (debug) and <STRONG>-n</STRONG> (no-op) options are extensions not provided by
218 other implementations.
221 </PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
222 A <STRONG>tabs</STRONG> utility appeared in PWB/Unix 1.0 (1977). A reduced version
223 shipped in Seventh Edition Unix (early 1979) and in 3BSD (later the
224 same year); it supported a "-n" option to set the first tab stop at the
225 left margin. That option is not documented by POSIX.
227 The PWB/Unix <STRONG>tabs</STRONG> utility returned in System III (1980), and used
228 built-in tables rather than the terminal database, to support a half-
229 dozen hardcopy terminal (printer) types. It also had built-in logic to
230 support setting the left margin, as well as a feature for copying the
231 tab settings from a file.
233 Versions of the program in later releases of AT&T Unix, such as SVr4,
234 added support for the terminal database, but retained the tables to
235 support the printers. In an earlier development effort, the tab stop
236 initialization provided by <STRONG><A HREF="tset.1.html">tset(1)</A></STRONG> (1982), and incorporated into
237 <STRONG><A HREF="tput.1.html">tput(1)</A></STRONG> uses the terminal database,
239 The <STRONG>+m</STRONG> option was documented in the POSIX Base Specifications Issue 5
240 (Unix98, 1997), then omitted in Issue 6 (Unix03, 2004) without express
241 motivation, though an introductory comment <EM>"and</EM> <EM>optionally</EM> <EM>adjusts</EM> <EM>the</EM>
242 <EM>margin"</EM> remains, overlooked in the removal. The <STRONG>tabs</STRONG> utility
243 documented in Issues 6 and later has no mechanism for setting margins.
244 The <STRONG>+m</STRONG> option in <EM>ncurses</EM> <STRONG>tabs</STRONG> differs from the SVr4 feature by using
245 terminal capabilities rather than built-in tables.
247 POSIX documents no limit on the number of tab stops. Other
248 implementations impose one; the limit is 20 in PWB/Unix's <STRONG>tabs</STRONG> utility.
249 While some terminals may not accept an arbitrary number of tab stops,
250 <EM>ncurses</EM> <STRONG>tabs</STRONG> attempts to set tab stops up to the right margin if the
251 list thereof is sufficiently long.
253 The "Rationale" section of the Issue 6 <STRONG>tabs</STRONG> reference page details how
254 the committee considered redesigning the <STRONG>tabs</STRONG> and <STRONG>tput</STRONG> utilities,
255 without settling on an improved solution. It claims that
257 no known historical version of tabs supports the capability of
258 setting arbitrary tab stops.
260 Nevertheless, the feature described in subsection "Explicit Lists"
261 above was implemented in PWB/Unix, and permits the setting of abitrary
265 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
266 <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>
270 ncurses 6.4 2023-12-16 <STRONG><A HREF="tabs.1.html">tabs(1)</A></STRONG>
274 <li><a href="#h2-NAME">NAME</a></li>
275 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
276 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
277 <li><a href="#h2-OPTIONS">OPTIONS</a>
279 <li><a href="#h3-General-Options">General Options</a></li>
280 <li><a href="#h3-Implicit-Lists">Implicit Lists</a></li>
281 <li><a href="#h3-Explicit-Lists">Explicit Lists</a></li>
282 <li><a href="#h3-Predefined-Tab-Stops">Predefined Tab-Stops</a></li>
283 <li><a href="#h3-Margins">Margins</a></li>
286 <li><a href="#h2-FILES">FILES</a></li>
287 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
288 <li><a href="#h2-HISTORY">HISTORY</a></li>
289 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>