tabs(1)

NAME

tabs — set tabs on a terminal

SYNOPSIS

tabs [tabspec] [+m n] [-T type]

DESCRIPTION

tabs sets the tab stops on the user's terminal according to the tab specification tabspec, after clearing any previous settings. The user's terminal must have remotely-settable hardware tabs.

If you are using a non-HP terminal, you should keep in mind that behavior will vary for some tab settings.

Four types of tab specification are accepted for tabspec: ``canned'', repetitive, arbitrary, and file. If no tabspec is given, the default value is -8; i.e., UNIX ``standard'' tabs. The lowest column number is 1. Note that for tabs, column 1 always refers to the left-most column on a terminal, even one whose column markers begin at 0.

-code

Gives the name of one of a set of ``canned'' tabs. Recognized codes and their meanings are as follows:

-a: 1,10,16,36,72 Assembler, IBM S/370, first format
-a2: 1,10,16,40,72 Assembler, IBM S/370, second format
-c: 1,8,12,16,20,55 COBOL, normal format
-c2: 1,6,10,14,49 COBOL compact format (columns 1-6 omitted). Using this code, the first typed character corresponds to card column 7, one space gets you to column 8, and a tab reaches column 12. Files using this tab setup should have tabs specify a format specification file as defined by --file below. The file should have the following format specification:
<:t-c2 m6 s66 d:>
-c3: 1,6,10,14,18,22,26,30,34,38,42,46,50,54,58,62,67 COBOL compact format (columns 1-6 omitted), with more tabs than -c2. This is the recommended format for COBOL. The appropriate format specification is:
<:t-c3 m6 s66 d:>
-f: 1,7,11,15,19,23 FORTRAN
-p: 1,5,9,13,17,21,25,29,33,37,41,45,49,53,57,61 PL/I
-s: 1,10,55 SNOBOL
-u: 1,12,20,44 UNIVAC 1100 Assembler

In addition to these ``canned'' formats, three other types exist:

-n: A repetitive specification requests tabs at columns 1+n, 1+2×n, etc. Of particular importance is the value -8: this represents the UNIX ``standard'' tab setting, and is the most likely tab setting to be found at a terminal. Another special case is the value -0, implying no tabs at all.
n1,n2,...: The arbitrary format permits the user to type any chosen set of numbers, separated by commas, in ascending order. Up to 40 numbers are allowed. If any number (except the first one) is preceded by a plus sign, it is taken as an increment to be added to the previous value. Thus, the tab lists 1,10,20,30 and 1,10,+10,+10 are considered identical.
--file: If the name of a file is given, tabs reads the first line of the file, searching for a format specification. If it finds one there, it sets the tab stops according to it, otherwise it sets them as -8. This type of specification can be used to ensure that a tabbed file is printed with correct tab settings, and is suitable for use with the pr command (see pr(1)):
tabs -- file; pr file

Any of the following can be used also; if a given option occurs more than once, the last value given takes effect:

-Ttype: tabs usually needs to know the type of terminal in order to set tabs and always needs to know the type to set margins. type is a name listed in term(5). If no -T option is supplied, tabs searches for the $TERM value in the environment (see environ(5)). If TERM is not defined in the environment, tabs tries a sequence that will work for many terminals.
+mn: The margin argument can be used for some terminals. It causes all tabs to be moved over n columns by making column n+1 the left margin. If +m is given without a value of n, the value assumed is 10. The normal (left-most) margin on most terminals is obtained by +m0. The margin for most terminals is reset only when the +m option is given explicitly.

Tab and margin setting is performed via the standard output.

EXTERNAL INFLUENCES

Environment Variables

LC_CTYPE determines the interpretation of text within file as single- and/or multi-byte characters.

LC_MESSAGES determines the language in which messages are displayed.

If LC_CTYPE or LC_MESSAGES is not specified in the environment or is set to the empty string, the value of LANG is used as a default for each unspecified or empty variable. If LANG is not specified or is set to the empty string, a default of "C" (see lang(5)) is used instead of LANG.

If any internationalization variable contains an invalid setting, tabs behaves as if all internationalization variables are set to "C". See environ(5).

International Code Set Support

Single- and multi-byte character code sets are supported.

DIAGNOSTICS

illegal tabs: Arbitrary tabs are ordered incorrectly.
illegal increment: A zero or missing increment found in an arbitrary specification.
unknown tab code: A ``canned'' code cannot be found.
can't open: --file option was used and file cannot be opened.
file indirection: --file option was used and the specification in that file points to yet another file. Indirection of this form is not permitted.

WARNINGS

There is no consistency among different terminals regarding ways of clearing tabs and setting the left margin.

It is generally impossible to usefully change the left margin without also setting tabs.

tabs clears only 20 tabs (on terminals requiring a long sequence), but is willing to set 64.

STANDARDS CONFORMANCE

tabs: SVID2, SVID3, XPG2, XPG3, XPG4