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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., 62 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. 82 83 84</PRE><H2><a name="h2-OPTIONS">OPTIONS</a></H2><PRE> 85 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. 91 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. 96 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. 99 100 <STRONG>-V</STRONG> reports the version of <EM>ncurses</EM> which was used in this program, and 101 exits. 102 103 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. 106 107 108</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. 112 113 Use "<STRONG>-0</STRONG>" to clear all tabs. 114 115 Use "<STRONG>-8</STRONG>" to set tabs to the standard interval. 116 117 118</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, 123 124 tabs 1,6,11,16,21 125 tabs 1 6 11 16 21 126 127 Use a "+" to treat a number as an increment relative to the previous 128 value, e.g., 129 130 tabs 1,+5,+5,+5,+5 131 132 which is equivalent to the 1,6,11,16,21 example. 133 134 135</PRE><H3><a name="h3-Predefined-Tab-Stops">Predefined Tab Stops</a></H3><PRE> 136 POSIX defines several predefined lists of tab stops. 137 138 <STRONG>-a</STRONG> Assembler, IBM S/370, first format 139 1,10,16,36,72 140 141 <STRONG>-a2</STRONG> Assembler, IBM S/370, second format 142 1,10,16,40,72 143 144 <STRONG>-c</STRONG> COBOL, normal format 145 1,8,12,16,20,55 146 147 <STRONG>-c2</STRONG> COBOL compact format 148 1,6,10,14,49 149 150 <STRONG>-c3</STRONG> COBOL compact format extended 151 1,6,10,14,18,22,26,30,34,38,42,46,50,54,58,62,67 152 153 <STRONG>-f</STRONG> FORTRAN 154 1,7,11,15,19,23 155 156 <STRONG>-p</STRONG> PL/I 157 1,5,9,13,17,21,25,29,33,37,41,45,49,53,57,61 158 159 <STRONG>-s</STRONG> SNOBOL 160 1,10,55 161 162 <STRONG>-u</STRONG> UNIVAC 1100 Assembler 163 1,12,20,44 164 165 166</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. 169 170 <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 210 provided by other implementations. 211 212 213</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&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. 254 255 256</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> 258 259 260 261ncurses 6.5 2024-04-20 <STRONG><A HREF="tabs.1.html">tabs(1)</A></STRONG> 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> 273<li><a href="#h3-Predefined-Tab-Stops">Predefined Tab Stops</a></li> 274<li><a href="#h3-Margins">Margins</a></li> 275</ul> 276</li> 277<li><a href="#h2-FILES">FILES</a></li> 278<li><a href="#h2-PORTABILITY">PORTABILITY</a></li> 279<li><a href="#h2-HISTORY">HISTORY</a></li> 280<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li> 281</ul> 282</div> 283</BODY> 284</HTML> 285