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micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]30 * @Id: tabs.1,v 1.59 2024/04/20 19:08:15 tom Exp @
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32<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
33<HTML>
34<HEAD>
35<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]36<meta name="generator" content="Manpage converted by man2html - see https://invisible-island.net/scripts/readme.html#others_scripts">
37<TITLE>tabs 1 2024-04-20 ncurses 6.5 User commands</TITLE>
38<link rel="author" href="mailto:bug-ncurses@gnu.org">
39
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]40</HEAD>
41<BODY>
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]42<H1 class="no-header">tabs 1 2024-04-20 ncurses 6.5 User commands</H1>
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]43<PRE>
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]44<STRONG><A HREF="tabs.1.html">tabs(1)</A></STRONG> User commands <STRONG><A HREF="tabs.1.html">tabs(1)</A></STRONG>
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46
47
48
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]49</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
50 <STRONG>tabs</STRONG> - set terminal tab stops
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52
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]53</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
54 <STRONG>tabs</STRONG> [<EM>options</EM>] [<EM>tabstop-list</EM>]
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56
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]57</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
58 The <STRONG>tabs</STRONG> program clears and sets tab-stops on the terminal. This uses
59 the terminfo <STRONG>clear_all_tabs</STRONG> and <STRONG>set_tab</STRONG> capabilities. If either is
60 absent, <STRONG>tabs</STRONG> is unable to clear/set tab-stops. The terminal should be
61 configured to use hard tabs, e.g.,
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]62
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]63 stty tab0
64
65 Like <STRONG><A HREF="clear.1.html">clear(1)</A></STRONG>, <STRONG>tabs</STRONG> writes to the standard output. You can redirect
66 the standard output to a file (which prevents <STRONG>tabs</STRONG> from actually
67 changing the tabstops), and later <STRONG>cat</STRONG> the file to the screen, setting
68 tabstops at that point.
69
70 These are hardware tabs, which cannot be queried rapidly by
71 applications running in the terminal, if at all. Curses and other
72 full-screen applications may use hardware tabs in optimizing their
73 output to the terminal. If the hardware tabstops differ from the
74 information in the terminal database, the result is unpredictable.
75 Before running curses programs, you should either reset tab-stops to
76 the standard interval
77
78 tabs -8
79
80 or use the <STRONG>reset</STRONG> program, since the normal initialization sequences do
81 not ensure that tab-stops are reset.
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83
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]84</PRE><H2><a name="h2-OPTIONS">OPTIONS</a></H2><PRE>
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micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]86</PRE><H3><a name="h3-General-Options">General Options</a></H3><PRE>
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]87 <STRONG>-T</STRONG><EM>name</EM>
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]88 Tell <STRONG>tabs</STRONG> which terminal type to use. If this option is not
89 given, <STRONG>tabs</STRONG> will use the <STRONG>$TERM</STRONG> environment variable. If that is
90 not set, it will use the <EM>ansi+tabs</EM> entry.
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micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]92 <STRONG>-d</STRONG> The debugging option shows a ruler line, followed by two data
93 lines. The first data line shows the expected tab-stops marked
94 with asterisks. The second data line shows the actual tab-stops,
95 marked with asterisks.
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]96
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]97 <STRONG>-n</STRONG> This option tells <STRONG>tabs</STRONG> to check the options and run any debugging
98 option, but not to modify the terminal settings.
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micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]100 <STRONG>-V</STRONG> reports the version of <EM>ncurses</EM> which was used in this program, and
101 exits.
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micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]103 The <STRONG>tabs</STRONG> program processes a single list of tab stops. The last option
104 to be processed which defines a list is the one that determines the
105 list to be processed.
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107
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]108</PRE><H3><a name="h3-Implicit-Lists">Implicit Lists</a></H3><PRE>
109 Use a single number as an option, e.g., "<STRONG>-5</STRONG>" to set tabs at the given
110 interval (in this case 1, 6, 11, 16, 21, etc.). Tabs are repeated up
111 to the right margin of the screen.
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113 Use "<STRONG>-0</STRONG>" to clear all tabs.
114
115 Use "<STRONG>-8</STRONG>" to set tabs to the standard interval.
116
117
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]118</PRE><H3><a name="h3-Explicit-Lists">Explicit Lists</a></H3><PRE>
119 An explicit list can be defined after the options (this does not use a
120 "-"). The values in the list must be in increasing numeric order, and
121 greater than zero. They are separated by a comma or a blank, for
122 example,
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]123
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]124 tabs 1,6,11,16,21
125 tabs 1 6 11 16 21
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micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]127 Use a "+" to treat a number as an increment relative to the previous
128 value, e.g.,
129
130 tabs 1,+5,+5,+5,+5
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132 which is equivalent to the 1,6,11,16,21 example.
133
134
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]135</PRE><H3><a name="h3-Predefined-Tab-Stops">Predefined Tab Stops</a></H3><PRE>
136 POSIX defines several predefined lists of tab stops.
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138 <STRONG>-a</STRONG> Assembler, IBM S/370, first format
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141 <STRONG>-a2</STRONG> Assembler, IBM S/370, second format
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]142 1,10,16,40,72
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144 <STRONG>-c</STRONG> COBOL, normal format
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147 <STRONG>-c2</STRONG> COBOL compact format
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150 <STRONG>-c3</STRONG> COBOL compact format extended
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153 <STRONG>-f</STRONG> FORTRAN
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156 <STRONG>-p</STRONG> PL/I
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159 <STRONG>-s</STRONG> SNOBOL
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162 <STRONG>-u</STRONG> UNIVAC 1100 Assembler
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165
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]166</PRE><H3><a name="h3-Margins">Margins</a></H3><PRE>
167 A few terminals expose a means of changing their left and right
168 margins. <STRONG>tabs</STRONG> supports this feature with an option.
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]169
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]170 <STRONG>+m</STRONG> <EM>margin</EM>
171 The effect depends on whether the terminal has the margin
172 capabilities:
173
174 <STRONG>o</STRONG> If the terminal provides the capability for setting the left
175 margin, <STRONG>tabs</STRONG> uses this, and adjusts the available tab stop
176 widths.
177
178 <STRONG>o</STRONG> If the terminal does not provide the margin capabilities, <STRONG>tabs</STRONG>
179 imitates their effect, putting tab stops at appropriate places
180 on each line. The terminal's left margin is not modified.
181
182 If the <EM>margin</EM> parameter is omitted, the default is 10. Use <STRONG>+m0</STRONG> to
183 reset the left margin, that is, to make it the left edge of the
184 terminal's display. Before setting a left margin, <STRONG>tabs</STRONG> resets the
185 margin to reduce problems that might arise from moving the cursor
186 to the left of the current left margin.
187
188 When setting or resetting the left margin, <STRONG>tabs</STRONG> may also reset the
189 right margin.
190
191
192</PRE><H2><a name="h2-FILES">FILES</a></H2><PRE>
193 <EM>/usr/share/tabset</EM>
194 tab stop initialization database
195
196
197</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
198 IEEE Std 1003.1/The Open Group Base Specifications Issue 7
199 (POSIX.1-2008) describes a <STRONG>tabs</STRONG> utility. However,
200
201 <STRONG>o</STRONG> this standard describes a <STRONG>+m</STRONG> option to set a terminal's left
202 margin. Very few of the entries in the terminal database provide
203 the <STRONG>set_left_margin</STRONG> (<STRONG>smgl</STRONG>) or <STRONG>set_left_margin_parm</STRONG> (<STRONG>smglp</STRONG>)
204 capabilities needed to support the feature.
205
206 <STRONG>o</STRONG> There is no counterpart in X/Open Curses Issue 7 for this utility,
207 unlike <STRONG><A HREF="tput.1.html">tput(1)</A></STRONG>.
208
209 The <STRONG>-d</STRONG> (debug) and <STRONG>-n</STRONG> (no-op) options are <EM>ncurses</EM> extensions not
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]210 provided by other implementations.
211
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]212
213</PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
214 A <STRONG>tabs</STRONG> utility appeared in PWB/Unix 1.0 (1977). A reduced version
215 shipped in Seventh Edition Unix (early 1979) and in 3BSD (later the
216 same year); it supported a "-n" option to set the first tab stop at the
217 left margin. That option is not specified by POSIX.
218
219 The PWB/Unix <STRONG>tabs</STRONG> utility returned in System III (1980), and used
220 built-in tables to support a half-dozen hardcopy terminal (printer)
221 types. It also had logic to support setting the left margin, as well
222 as a feature for copying the tab settings from a file.
223
224 Versions of the program in later releases of AT&amp;T Unix, such as SVr4,
225 added support for the terminal database, but retained the tables to
226 support the printers. By this time, System V <STRONG>tput</STRONG> had incorporated the
227 tab stop initialization feature of BSD's <STRONG>tset</STRONG> from 1982, but employed
228 the <EM>terminfo</EM> database to do so.
229
230 The <STRONG>+m</STRONG> option was documented in the POSIX Base Specifications Issue 5
231 (Unix98, 1997), then omitted in Issue 6 (Unix03, 2004) without express
232 motivation, though an introductory comment "and optionally adjusts the
233 margin" remains, overlooked in the removal. The <STRONG>tabs</STRONG> utility
234 documented in Issues 6 and later has no mechanism for setting margins.
235 The <STRONG>+m</STRONG> option in <EM>ncurses</EM> <STRONG>tabs</STRONG> differs from the SVr4 feature by using
236 terminal capabilities rather than built-in tables.
237
238 POSIX documents no limit on the number of tab stops. Other
239 implementations impose one; the limit is 20 in PWB/Unix's <STRONG>tabs</STRONG> utility.
240 While some terminals may not accept an arbitrary number of tab stops,
241 <EM>ncurses</EM> <STRONG>tabs</STRONG> attempts to set tab stops up to the right margin if the
242 list thereof is sufficiently long.
243
244 The "Rationale" section of the Issue 6 <STRONG>tabs</STRONG> reference page details how
245 the committee considered redesigning the <STRONG>tabs</STRONG> and <STRONG>tput</STRONG> utilities,
246 without settling on an improved solution. It claims that
247
248 "no known historical version of <EM>tabs</EM> supports the capability of
249 setting arbitrary tab stops."
250
251 The feature described in subsection "Explicit Lists" above was
252 implemented in PWB/Unix, and permitted the setting of abitrary tab
253 stops nevertheless.
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255
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]256</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
257 <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>
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259
260
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]261ncurses 6.5 2024-04-20 <STRONG><A HREF="tabs.1.html">tabs(1)</A></STRONG>
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]262</PRE>
263<div class="nav">
264<ul>
265<li><a href="#h2-NAME">NAME</a></li>
266<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
267<li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
268<li><a href="#h2-OPTIONS">OPTIONS</a>
269<ul>
270<li><a href="#h3-General-Options">General Options</a></li>
271<li><a href="#h3-Implicit-Lists">Implicit Lists</a></li>
272<li><a href="#h3-Explicit-Lists">Explicit Lists</a></li>
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]273<li><a href="#h3-Predefined-Tab-Stops">Predefined Tab Stops</a></li>
274<li><a href="#h3-Margins">Margins</a></li>
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]275</ul>
276</li>
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]277<li><a href="#h2-FILES">FILES</a></li>
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]278<li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
micky3879b9f5e72025-07-08 18:04:53 -0400[diff] [blame]279<li><a href="#h2-HISTORY">HISTORY</a></li>
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]280<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
281</ul>
282</div>
283</BODY>
284</HTML>