1TABS(1P) POSIX Programmer's Manual TABS(1P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 tabs - set terminal tabs
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15 tabs [ -n| -a| -a2| -c| -c2| -c3| -f| -p| -s| -u][+m[n]] [-T type]
16 tabs [-T type][ +[n]] n1[,n2,...]
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21 The tabs utility shall display a series of characters that first clears
22 the hardware terminal tab settings and then initializes the tab stops
23 at the specified positions and optionally adjusts the margin.
24 The phrase "tab-stop position N" shall be taken to mean that, from the
26 start of a line of output, tabbing to position N shall cause the next
27 character output to be in the ( N+1)th column position on that line.
28 The maximum number of tab stops allowed is terminal-dependent.
29 It need not be possible to implement tabs on certain terminals. If the
31 terminal type obtained from the TERM environment variable or -T option
32 represents such a terminal, an appropriate diagnostic message shall be
33 written to standard error and tabs shall exit with a status greater
34 than zero.
35
37 The tabs utility shall conform to the Base Definitions volume of
38 IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines, except
39 for various extensions: the options -a2, -c2, and -c3 are multi-charac‐
40 ter.
41 The following options shall be supported:
43 -n Specify repetitive tab stops separated by a uniform number of
45 column positions, n, where n is a single-digit decimal number.
46 The default usage of tabs with no arguments shall be equivalent
47 to tabs-8. When -0 is used, the tab stops shall be cleared and
48 no new ones set.
49 -a 1,10,16,36,72
51 Assembler, applicable to some mainframes.
52 -a2 1,10,16,40,72
54 Assembler, applicable to some mainframes.
55 -c 1,8,12,16,20,55
57 COBOL, normal format.
58 -c2 1,6,10,14,49
60 COBOL, compact format (columns 1 to 6 omitted).
61 -c3 1,6,10,14,18,22,26,30,34,38,42,46,50,54,58,62,67
63 COBOL compact format (columns 1 to 6 omitted), with more tabs
64 than -c2.
65 -f 1,7,11,15,19,23
67 FORTRAN
68 -p 1,5,9,13,17,21,25,29,33,37,41,45,49,53,57,61
70 PL/1
71 -s 1,10,55
73 SNOBOL
74 -u 1,12,20,44
76 Assembler, applicable to some mainframes.
77 -T type
79 Indicate the type of terminal. If this option is not supplied
80 and the TERM variable is unset or null, an unspecified default
81 terminal type shall be used. The setting of type shall take
82 precedence over the value in TERM.
83
86 The following operand shall be supported:
87 n1[,n2,...]
89 A single command line argument that consists of tab-stop values
90 separated using either commas or <blank>s. The application shall
91 ensure that the tab-stop values are positive decimal integers in
92 strictly ascending order. If any number (except the first one)
93 is preceded by a plus sign, it is taken as an increment to be
94 added to the previous value. For example, the tab lists
95 1,10,20,30 and 1,10,+10,+10 are considered to be identical.
96
99 Not used.
100
102 None.
103
105 The following environment variables shall affect the execution of tabs:
106 LANG Provide a default value for the internationalization variables
108 that are unset or null. (See the Base Definitions volume of
109 IEEE Std 1003.1-2001, Section 8.2, Internationalization Vari‐
110 ables for the precedence of internationalization variables used
111 to determine the values of locale categories.)
112 LC_ALL If set to a non-empty string value, override the values of all
114 the other internationalization variables.
115 LC_CTYPE
117 Determine the locale for the interpretation of sequences of
118 bytes of text data as characters (for example, single-byte as
119 opposed to multi-byte characters in arguments).
120 LC_MESSAGES
122 Determine the locale that should be used to affect the format
123 and contents of diagnostic messages written to standard error.
124 NLSPATH
126 Determine the location of message catalogs for the processing of
127 LC_MESSAGES .
128 TERM Determine the terminal type. If this variable is unset or null,
130 and if the -T option is not specified, an unspecified default
131 terminal type shall be used.
132
135 Default.
136
138 If standard output is a terminal, the appropriate sequence to clear and
139 set the tab stops may be written to standard output in an unspecified
140 format. If standard output is not a terminal, undefined results occur.
141
143 The standard error shall be used only for diagnostic messages.
144
146 None.
147
149 None.
150
152 The following exit values shall be returned:
153 0 Successful completion.
155 >0 An error occurred.
157
160 Default.
161 The following sections are informative.
163
165 This utility makes use of the terminal's hardware tabs and the stty
166 tabs option.
167 This utility is not recommended for application use.
169 Some integrated display units might not have escape sequences to set
171 tab stops, but may be set by internal system calls. On these terminals,
172 tabs works if standard output is directed to the terminal; if output is
173 directed to another file, however, tabs fails.
174
176 None.
177
179 Consideration was given to having the tput utility handle all of the
180 functions described in tabs. However, the separate tabs utility was
181 retained because it seems more intuitive to use a command named tabs
182 than tput with a new option. The tput utility does not support setting
183 or clearing tabs, and no known historical version of tabs supports the
184 capability of setting arbitrary tab stops.
185 The System V tabs interface is very complex; the version in this volume
187 of IEEE Std 1003.1-2001 has a reduced feature list, but many of the
188 features omitted were restored as XSI extensions even though the sup‐
189 ported languages and coding styles are primarily historical.
190 There was considerable sentiment for specifying only a means of reset‐
192 ting the tabs back to a known state-presumably the "standard" of tabs
193 every eight positions. The following features were omitted:
194 * Setting tab stops via the first line in a file, using -- file.
196 Since even the SVID has no complete explanation of this feature, it
197 is doubtful that it is in widespread use.
198 In an early proposal, a -t tablist option was added for consistency
200 with expand; this was later removed when inconsistencies with the his‐
201 torical list of tabs were identified.
202 Consideration was given to adding a -p option that would output the
204 current tab settings so that they could be saved and then later
205 restored. This was not accepted because querying the tab stops of the
206 terminal is not a capability in historical terminfo or termcap facili‐
207 ties and might not be supported on a wide range of terminals.
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210 None.
211
213 expand, stty, tput, unexpand
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216 Portions of this text are reprinted and reproduced in electronic form
217 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
218 -- Portable Operating System Interface (POSIX), The Open Group Base
219 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
220 Electrical and Electronics Engineers, Inc and The Open Group. In the
221 event of any discrepancy between this version and the original IEEE and
222 The Open Group Standard, the original IEEE and The Open Group Standard
223 is the referee document. The original Standard can be obtained online
224 at http://www.opengroup.org/unix/online.html .
225IEEE/The Open Group 2003 TABS(1P)