tabs(1p) — Linux manual page


TABS(1P)                POSIX Programmer's Manual               TABS(1P)

PROLOG         top

       This manual page is part of the POSIX Programmer's Manual.  The
       Linux implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior),
       or the interface may not be implemented on Linux.

NAME         top

       tabs — set terminal tabs

SYNOPSIS         top

       tabs [-n|-a|-a2|-c|-c2|-c3|-f|-p|-s|-u] [-T type]

       tabs [-T type] n[[sep[+]n]...]

DESCRIPTION         top

       The tabs utility shall display a series of characters that first
       clears the hardware terminal tab settings and then initializes
       the tab stops at the specified positions and optionally adjusts
       the margin.

       The phrase ``tab-stop position N'' shall be taken to mean that,
       from the start of a line of output, tabbing to position N shall
       cause the next character output to be in the (N+1)th column
       position on that line. The maximum number of tab stops allowed is

       It need not be possible to implement tabs on certain terminals.
       If the terminal type obtained from the TERM environment variable
       or -T option represents such a terminal, an appropriate
       diagnostic message shall be written to standard error and tabs
       shall exit with a status greater than zero.

OPTIONS         top

       The tabs utility shall conform to the Base Definitions volume of
       POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines, except for
       various extensions: the options -a2, -c2, and -c3 are multi-

       The following options shall be supported:

       -n        Specify repetitive tab stops separated by a uniform
                 number of column positions, n, where n is a single-
                 digit decimal number. The default usage of tabs with no
                 arguments shall be equivalent to tabs -8. When -0 is
                 used, the tab stops shall be cleared and no new ones

       -a        1,10,16,36,72
                 Assembler, applicable to some mainframes.

       -a2       1,10,16,40,72
                 Assembler, applicable to some mainframes.

       -c        1,8,12,16,20,55
                 COBOL, normal format.

       -c2       1,6,10,14,49
                 COBOL, compact format (columns 1 to 6 omitted).

       -c3       1,6,10,14,18,22,26,30,34,38,42,46,50,54,58,62,67
                 COBOL compact format (columns 1 to 6 omitted), with
                 more tabs than -c2.

       -f        1,7,11,15,19,23

       -p        1,5,9,13,17,21,25,29,33,37,41,45,49,53,57,61

       -s        1,10,55

       -u        1,12,20,44
                 Assembler, applicable to some mainframes.

       -T type   Indicate the type of terminal. If this option is not
                 supplied and the TERM variable is unset or null, an
                 unspecified default terminal type shall be used. The
                 setting of type shall take precedence over the value in

OPERANDS         top

       The following operand shall be supported:

                 A single command line argument that consists of one or
                 more tab-stop values (n) separated by a separator
                 character (sep) which is either a <comma> or a <blank>
                 character. The application shall ensure that the tab-
                 stop values are positive decimal integers in strictly
                 ascending order. If any tab-stop value (except the
                 first one) is preceded by a <plus-sign>, it is taken as
                 an increment to be added to the previous value. For
                 example, the tab lists 1,10,20,30 and "110+10+10" are
                 considered to be identical.

STDIN         top

       Not used.

INPUT FILES         top



       The following environment variables shall affect the execution of

       LANG      Provide a default value for the internationalization
                 variables that are unset or null. (See the Base
                 Definitions volume of POSIX.1‐2017, Section 8.2,
                 Internationalization Variables for the precedence of
                 internationalization variables used to determine the
                 values of locale categories.)

       LC_ALL    If set to a non-empty string value, override the values
                 of all the other internationalization variables.

       LC_CTYPE  Determine the locale for the interpretation of
                 sequences of bytes of text data as characters (for
                 example, single-byte as opposed to multi-byte
                 characters in arguments).

                 Determine the locale that should be used to affect the
                 format and contents of diagnostic messages written to
                 standard error.

       NLSPATH   Determine the location of message catalogs for the
                 processing of LC_MESSAGES.

       TERM      Determine the terminal type. If this variable is unset
                 or null, and if the -T option is not specified, an
                 unspecified default terminal type shall be used.



STDOUT         top

       If standard output is a terminal, the appropriate sequence to
       clear and set the tab stops may be written to standard output in
       an unspecified format. If standard output is not a terminal,
       undefined results occur.

STDERR         top

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES         top




EXIT STATUS         top

       The following exit values shall be returned:

        0    Successful completion.

       >0    An error occurred.



       The following sections are informative.


       This utility makes use of the terminal's hardware tabs and the
       stty tabs option.

       This utility is not recommended for application use.

       Some integrated display units might not have escape sequences to
       set tab stops, but may be set by internal system calls. On these
       terminals, tabs works if standard output is directed to the
       terminal; if output is directed to another file, however, tabs

EXAMPLES         top


RATIONALE         top

       Consideration was given to having the tput utility handle all of
       the functions described in tabs.  However, the separate tabs
       utility was retained because it seems more intuitive to use a
       command named tabs than tput with a new option. The tput utility
       does not support setting or clearing tabs, and no known
       historical version of tabs supports the capability of setting
       arbitrary tab stops.

       The System V tabs interface is very complex; the version in this
       volume of POSIX.1‐2017 has a reduced feature list, but many of
       the features omitted were restored as part of the XSI option even
       though the supported languages and coding styles are primarily

       There was considerable sentiment for specifying only a means of
       resetting the tabs back to a known state—presumably the
       ``standard'' of tabs every eight positions. The following
       features were omitted:

        *  Setting tab stops via the first line in a file, using --file.
           Since even the SVID has no complete explanation of this
           feature, it is doubtful that it is in widespread use.

       In an early proposal, a -t tablist option was added for
       consistency with expand; this was later removed when
       inconsistencies with the historical list of tabs were identified.

       Consideration was given to adding a -p option that would output
       the current tab settings so that they could be saved and then
       later restored. This was not accepted because querying the tab
       stops of the terminal is not a capability in historical terminfo
       or termcap facilities and might not be supported on a wide range
       of terminals.



SEE ALSO         top

       expand(1p), stty(1p), tput(1p), unexpand(1p)

       The Base Definitions volume of POSIX.1‐2017, Chapter 8,
       Environment Variables, Section 12.2, Utility Syntax Guidelines

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  In the event of any
       discrepancy between this version and the original IEEE and The
       Open Group Standard, the original IEEE and The Open Group
       Standard is the referee document. The original Standard can be
       obtained online at .

       Any typographical or formatting errors that appear in this page
       are most likely to have been introduced during the conversion of
       the source files to man page format. To report such errors, see .

IEEE/The Open Group               2017                          TABS(1P)

Pages that refer to this page: expand(1p)tput(1p)unexpand(1p)