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30 * @Id: tabs.1,v 1.28 2020/12/19 21:50:22 tom Exp @
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42 <H1 class="no-header">tabs 1</H1>
44 <STRONG><A HREF="tabs.1.html">tabs(1)</A></STRONG> General Commands Manual <STRONG><A HREF="tabs.1.html">tabs(1)</A></STRONG>
49 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
50 <STRONG>tabs</STRONG> - set tabs on a terminal
53 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
54 <STRONG>tabs</STRONG> [<EM>options</EM>]] <EM>[tabstop-list]</EM>
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 <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
60 absent, <STRONG>tabs</STRONG> is unable to clear/set tab-stops. The terminal should be
61 configured to use hard tabs, e.g.,
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.
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
80 or use the <STRONG>reset</STRONG> program, since the normal initialization sequences do
81 not ensure that tab-stops are reset.
84 </PRE><H2><a name="h2-OPTIONS">OPTIONS</a></H2><PRE>
86 </PRE><H3><a name="h3-General-Options">General Options</a></H3><PRE>
87 <STRONG>-T</STRONG><EM>name</EM>
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.
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.
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.
100 <STRONG>-V</STRONG> reports the version of ncurses which was used in this program, and
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.
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.
113 Use "<STRONG>-0</STRONG>" to clear all tabs.
115 Use "<STRONG>-8</STRONG>" to set tabs to the standard interval.
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
127 Use a "+" to treat a number as an increment relative to the previous
132 which is equivalent to the 1,6,11,16,21 example.
135 </PRE><H3><a name="h3-Predefined-Tab-Stops">Predefined Tab-Stops</a></H3><PRE>
136 X/Open defines several predefined lists of tab stops.
138 <STRONG>-a</STRONG> Assembler, IBM S/370, first format
140 <STRONG>-a2</STRONG> Assembler, IBM S/370, second format
142 <STRONG>-c</STRONG> COBOL, normal format
144 <STRONG>-c2</STRONG> COBOL compact format
146 <STRONG>-c3</STRONG> COBOL compact format extended
148 <STRONG>-f</STRONG> FORTRAN
150 <STRONG>-p</STRONG> PL/I
152 <STRONG>-s</STRONG> SNOBOL
154 <STRONG>-u</STRONG> UNIVAC 1100 Assembler
157 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
158 <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>
159 (POSIX.1-2008) describes a <STRONG>tabs</STRONG> utility. However
161 <STRONG>o</STRONG> This standard describes a <STRONG>+m</STRONG> option, to set a terminal's left-
162 margin. Very few of the entries in the terminal database provide
163 the <STRONG>smgl</STRONG> (<STRONG>set_left_margin</STRONG>) or <STRONG>smglp</STRONG> (<STRONG>set_left_margin_parm</STRONG>)
164 capability needed to support the feature.
166 <STRONG>o</STRONG> There is no counterpart in X/Open Curses Issue 7 for this utility,
167 unlike <STRONG>tput(1)</STRONG>.
169 The <STRONG>-d</STRONG> (debug) and <STRONG>-n</STRONG> (no-op) options are extensions not provided by
170 other implementations.
172 A <STRONG>tabs</STRONG> utility appeared in PWB/Unix 1.0 (1977). There was a reduced
173 version of the <STRONG>tabs</STRONG> utility in Unix 7th edition and in 3BSD (1979).
174 The latter supported a single "-n" option (to cause the first tab stop
175 to be set on the left margin). That option is not documented by POSIX.
177 The PWB/Unix <STRONG>tabs</STRONG> utility, which was included in System III (1980),
178 used built-in tables rather than the terminal database, to support a
179 half-dozen terminal types. It also had built-in logic to support the
180 left-margin, as well as a feature for copying the tab settings from a
183 Later versions of Unix, e.g., SVr4, added support for the terminal
184 database, but kept the tables, as a fallback. In an earlier
185 development effort, the tab-stop initialization provided by <STRONG>tset</STRONG> (1982)
186 and incorporated into <STRONG>tput</STRONG> uses the terminal database,
188 POSIX documents no limits on the number of tab stops. Documentation
189 for other implementations states that there is a limit on the number of
190 tab stops (e.g., 20 in PWB/Unix's <STRONG>tabs</STRONG> utility). While some terminals
191 may not accept an arbitrary number of tab stops, this implementation
192 will attempt to set tab stops up to the right margin of the screen, if
193 the given list happens to be that long.
195 The <EM>Rationale</EM> section of the POSIX documentation goes into some detail
196 about the ways the committee considered redesigning the <STRONG>tabs</STRONG> and <STRONG>tput</STRONG>
197 utilities, without proposing an improved solution. It comments that
199 no known historical version of tabs supports the capability of
200 setting arbitrary tab stops.
202 However, the <EM>Explicit</EM> <EM>Lists</EM> described in this manual page were
203 implemented in PWB/Unix. Those provide the capability of setting
207 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
208 <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>.
210 This describes <STRONG>ncurses</STRONG> version 6.2 (patch 20210327).
214 <STRONG><A HREF="tabs.1.html">tabs(1)</A></STRONG>
218 <li><a href="#h2-NAME">NAME</a></li>
219 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
220 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
221 <li><a href="#h2-OPTIONS">OPTIONS</a>
223 <li><a href="#h3-General-Options">General Options</a></li>
224 <li><a href="#h3-Implicit-Lists">Implicit Lists</a></li>
225 <li><a href="#h3-Explicit-Lists">Explicit Lists</a></li>
226 <li><a href="#h3-Predefined-Tab-Stops">Predefined Tab-Stops</a></li>
229 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
230 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>