1TABS(P) POSIX Programmer's Manual TABS(P)
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6 tabs - set terminal tabs
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9 tabs [ -n| -a| -a2| -c| -c2| -c3| -f| -p| -s| -u][+m[n]] [-T type]
10 tabs [-T type][ +[n]] n1[,n2,...]
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15 The tabs utility shall display a series of characters that first clears
16 the hardware terminal tab settings and then initializes the tab stops
17 at the specified positions and optionally adjusts the margin.
18 The phrase "tab-stop position N" shall be taken to mean that, from the
20 start of a line of output, tabbing to position N shall cause the next
21 character output to be in the ( N+1)th column position on that line.
22 The maximum number of tab stops allowed is terminal-dependent.
23 It need not be possible to implement tabs on certain terminals. If the
25 terminal type obtained from the TERM environment variable or -T option
26 represents such a terminal, an appropriate diagnostic message shall be
27 written to standard error and tabs shall exit with a status greater
28 than zero.
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31 The tabs utility shall conform to the Base Definitions volume of
32 IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines, except
33 for various extensions: the options -a2, -c2, and -c3 are multi-charac‐
34 ter.
35 The following options shall be supported:
37 -n Specify repetitive tab stops separated by a uniform number of
39 column positions, n, where n is a single-digit decimal number.
40 The default usage of tabs with no arguments shall be equivalent
41 to tabs-8. When -0 is used, the tab stops shall be cleared and
42 no new ones set.
43 -a 1,10,16,36,72
45 Assembler, applicable to some mainframes.
46 -a2 1,10,16,40,72
48 Assembler, applicable to some mainframes.
49 -c 1,8,12,16,20,55
51 COBOL, normal format.
52 -c2 1,6,10,14,49
54 COBOL, compact format (columns 1 to 6 omitted).
55 -c3 1,6,10,14,18,22,26,30,34,38,42,46,50,54,58,62,67
57 COBOL compact format (columns 1 to 6 omitted), with more tabs
58 than -c2.
59 -f 1,7,11,15,19,23
61 FORTRAN
62 -p 1,5,9,13,17,21,25,29,33,37,41,45,49,53,57,61
64 PL/1
65 -s 1,10,55
67 SNOBOL
68 -u 1,12,20,44
70 Assembler, applicable to some mainframes.
71 -T type
73 Indicate the type of terminal. If this option is not supplied
74 and the TERM variable is unset or null, an unspecified default
75 terminal type shall be used. The setting of type shall take
76 precedence over the value in TERM .
77
80 The following operand shall be supported:
81 n1[,n2,...]
83 A single command line argument that consists of tab-stop values
84 separated using either commas or <blank>s. The application shall
85 ensure that the tab-stop values are positive decimal integers in
86 strictly ascending order. If any number (except the first one)
87 is preceded by a plus sign, it is taken as an increment to be
88 added to the previous value. For example, the tab lists
89 1,10,20,30 and 1,10,+10,+10 are considered to be identical.
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93 Not used.
94
96 None.
97
99 The following environment variables shall affect the execution of tabs:
100 LANG Provide a default value for the internationalization variables
102 that are unset or null. (See the Base Definitions volume of
103 IEEE Std 1003.1-2001, Section 8.2, Internationalization Vari‐
104 ables for the precedence of internationalization variables used
105 to determine the values of locale categories.)
106 LC_ALL If set to a non-empty string value, override the values of all
108 the other internationalization variables.
109 LC_CTYPE
111 Determine the locale for the interpretation of sequences of
112 bytes of text data as characters (for example, single-byte as
113 opposed to multi-byte characters in arguments).
114 LC_MESSAGES
116 Determine the locale that should be used to affect the format
117 and contents of diagnostic messages written to standard error.
118 NLSPATH
120 Determine the location of message catalogs for the processing of
121 LC_MESSAGES .
122 TERM Determine the terminal type. If this variable is unset or null,
124 and if the -T option is not specified, an unspecified default
125 terminal type shall be used.
126
129 Default.
130
132 If standard output is a terminal, the appropriate sequence to clear and
133 set the tab stops may be written to standard output in an unspecified
134 format. If standard output is not a terminal, undefined results occur.
135
137 The standard error shall be used only for diagnostic messages.
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140 None.
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143 None.
144
146 The following exit values shall be returned:
147 0 Successful completion.
149 >0 An error occurred.
151
154 Default.
155 The following sections are informative.
157
159 This utility makes use of the terminal's hardware tabs and the stty
160 tabs option.
161 This utility is not recommended for application use.
163 Some integrated display units might not have escape sequences to set
165 tab stops, but may be set by internal system calls. On these terminals,
166 tabs works if standard output is directed to the terminal; if output is
167 directed to another file, however, tabs fails.
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170 None.
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173 Consideration was given to having the tput utility handle all of the
174 functions described in tabs. However, the separate tabs utility was
175 retained because it seems more intuitive to use a command named tabs
176 than tput with a new option. The tput utility does not support setting
177 or clearing tabs, and no known historical version of tabs supports the
178 capability of setting arbitrary tab stops.
179 The System V tabs interface is very complex; the version in this volume
181 of IEEE Std 1003.1-2001 has a reduced feature list, but many of the
182 features omitted were restored as XSI extensions even though the sup‐
183 ported languages and coding styles are primarily historical.
184 There was considerable sentiment for specifying only a means of reset‐
186 ting the tabs back to a known state-presumably the "standard" of tabs
187 every eight positions. The following features were omitted:
188 * Setting tab stops via the first line in a file, using -- file.
190 Since even the SVID has no complete explanation of this feature, it
191 is doubtful that it is in widespread use.
192 In an early proposal, a -t tablist option was added for consistency
194 with expand; this was later removed when inconsistencies with the his‐
195 torical list of tabs were identified.
196 Consideration was given to adding a -p option that would output the
198 current tab settings so that they could be saved and then later
199 restored. This was not accepted because querying the tab stops of the
200 terminal is not a capability in historical terminfo or termcap facili‐
201 ties and might not be supported on a wide range of terminals.
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204 None.
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207 expand , stty , tput , unexpand
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210 Portions of this text are reprinted and reproduced in electronic form
211 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
212 -- Portable Operating System Interface (POSIX), The Open Group Base
213 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
214 Electrical and Electronics Engineers, Inc and The Open Group. In the
215 event of any discrepancy between this version and the original IEEE and
216 The Open Group Standard, the original IEEE and The Open Group Standard
217 is the referee document. The original Standard can be obtained online
218 at http://www.opengroup.org/unix/online.html .
219IEEE/The Open Group 2003 TABS(P)