.\" authorization. *
.\"***************************************************************************
.\"
-.\" $Id: tabs.1,v 1.44 2023/09/16 23:38:39 tom Exp $
-.TH @TABS@ 1 2023-09-16 "ncurses 6.4" "User commands"
-.ds n 5
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+.\" $Id: tabs.1,v 1.52 2023/12/23 16:08:25 tom Exp $
+.TH @TABS@ 1 2023-12-23 "ncurses 6.4" "User commands"
+.ie \n(.g \{\
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+.\}
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+.ie t .ds `` ``
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+.ie t .ds '' ''
+.el .ds '' ""
+.\}
+.
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+.
.SH NAME
\fB\%@TABS@\fP \-
set terminal tab stops
.SH SYNOPSIS
-\fB@TABS@\fP [\fIoptions\fP]] \fI[tabstop-list]\fP
+\fB@TABS@\fP [\fIoptions\fP] [\fItabstop-list\fP]
.SH DESCRIPTION
The \fB@TABS@\fP program clears and sets tab-stops on the terminal.
This uses the terminfo \fBclear_all_tabs\fP and \fBset_tab\fP capabilities.
If either is absent, \fB@TABS@\fP is unable to clear/set tab-stops.
The terminal should be configured to use hard tabs, e.g.,
-.NS
+.PP
+.RS 4
+.EX
stty tab0
-.NE
+.EE
+.RE
.PP
Like \fB@CLEAR@\fP(1), \fB@TABS@\fP writes to the standard output.
You can redirect the standard output to a file (which prevents
database, the result is unpredictable.
Before running curses programs,
you should either reset tab-stops to the standard interval
-.NS
-tabs -8
-.NE
+.PP
+.RS 4
+.EX
+tabs \-8
+.EE
+.RE
.PP
or use the \fB@RESET@\fP program,
since the normal initialization sequences do not ensure that tab-stops
are reset.
.SH OPTIONS
-.SS General Options
+.SS "General Options"
.TP 5
.BI \-T "name"
Tell \fB@TABS@\fP which terminal type to use.
option, but not to modify the terminal settings.
.TP
\fB\-V\fP
-reports the version of ncurses which was used in this program, and exits.
+reports the version of \fI\%ncurses\fP which was used in this program,
+and exits.
.PP
The \fB@TABS@\fP program processes a single list of tab stops.
The last option to be processed which defines a list is the one that
determines the list to be processed.
-.SS Implicit Lists
+.SS "Implicit Lists"
Use a single number as an option,
e.g., \*(``\fB\-5\fP\*('' to set tabs at the given
interval (in this case 1, 6, 11, 16, 21, etc.).
Use \*(``\fB\-0\fP\*('' to clear all tabs.
.PP
Use \*(``\fB\-8\fP\*('' to set tabs to the standard interval.
-.SS Explicit Lists
+.SS "Explicit Lists"
An explicit list can be defined after the options
(this does not use a \*(``\-\*('').
The values in the list must be in increasing numeric order,
and greater than zero.
They are separated by a comma or a blank, for example,
-.NS
+.PP
+.RS 4
+.EX
tabs 1,6,11,16,21
-.br
tabs 1 6 11 16 21
-.NE
+.EE
+.RE
.PP
Use a \*(``+\*('' to treat a number
as an increment relative to the previous value,
e.g.,
-.NS
+.PP
+.RS 4
+.EX
tabs 1,+5,+5,+5,+5
-.NE
+.EE
+.RE
.PP
which is equivalent to the 1,6,11,16,21 example.
-.SS Predefined Tab-Stops
+.SS "Predefined Tab Stops"
POSIX defines several predefined lists of tab stops.
.TP 5
.B \-a
.PP
When setting or resetting the left-margin,
@TABS@ may reset the right-margin.
+.SH FILES
+.TP
+.I @DATADIR@/tabset
+tab stop initialization database
.SH PORTABILITY
\fIIEEE Std 1003.1/The Open Group Base Specifications Issue 7\fP (POSIX.1-2008)
describes a \fBtabs\fP utility.
.PP
The \fB\-d\fP (debug) and \fB\-n\fP (no-op) options are extensions not provided
by other implementations.
-.PP
+.SH HISTORY
A \fBtabs\fP utility appeared in PWB/Unix 1.0 (1977).
-There was a reduced version of the \fBtabs\fP utility
-in Unix 7th edition and in 3BSD (1979).
-The latter supported a single \*(``\-n\*('' option
-(to cause the first tab stop to be set on the left margin).
+.\" https://minnie.tuhs.org/cgi-bin/utree.pl?file=PWB1/sys/source/s2/\
+.\" tabs.c
+A reduced version shipped in Seventh Edition Unix
+(early 1979)
+.\" https://minnie.tuhs.org/cgi-bin/utree.pl?file=V7/usr/src/cmd/tabs.c
+and in 3BSD
+.\" https://minnie.tuhs.org/cgi-bin/utree.pl?file=3BSD/usr/src/cmd/\
+.\" tabs.c
+(later the same year);
+it supported a \*(``\-n\*('' option to set the first tab stop at the
+left margin.
That option is not documented by POSIX.
.PP
-The PWB/Unix \fBtabs\fP utility, which was included in System III (1980),
-used built-in tables rather than the terminal database,
+The PWB/Unix \fBtabs\fP utility returned in System III (1980),
+and used built-in tables rather than the terminal database,
to support a half-dozen hardcopy terminal (printer) types.
-It also had built-in logic to support the left-margin,
+It also had built-in logic to support setting the left margin,
as well as a feature for copying the tab settings from a file.
.PP
-Later versions of Unix, e.g., SVr4,
+Versions of the program in later releases of AT&T Unix,
+such as SVr4,
+.\" https://minnie.tuhs.org/cgi-bin/utree.pl?file=SysVR4/cmd/tabs/tabs.c
added support for the terminal database,
-but kept the tables to support the printers.
+but retained the tables to support the printers.
In an earlier development effort,
-the tab-stop initialization provided by \fBtset\fP (1982)
-and incorporated into \fBtput\fP uses the terminal database,
+the tab stop initialization provided by \fBtset\fP(1) (1982),
+and incorporated into \fBtput\fP(1) uses the terminal database,
.PP
-The \fB+m\fP option was documented
-in the Base Specifications Issue 5 (Unix98, 1997),
-and omitted in Issue 6 (Unix03, 2004) without documenting the rationale,
+The \fB+m\fP option was documented in the POSIX
+Base Specifications Issue 5
+(Unix98, 1997),
+then omitted in Issue 6
+(Unix03, 2004)
+without express motivation,
though an introductory comment
\fI\*(``and optionally adjusts the margin\*(''\fP remains,
overlooked in the removal.
-The documented \fBtabs\fP utility in Issues 6 and later has no mechanism
+The \fBtabs\fP utility documented in Issues 6 and later has no mechanism
for setting margins.
-The \fB+m\fP option in this implementation differs from the feature
-in SVr4 by using terminal capabilities rather than built-in tables.
+The \fB+m\fP option in
+.I \%ncurses
+\fBtabs\fP differs from the SVr4 feature by using terminal capabilities
+rather than built-in tables.
.PP
-POSIX documents no limits on the number of tab stops.
-Documentation for other implementations states that there is a limit on the
-number of tab stops
-(e.g., 20 in PWB/Unix's \fBtabs\fP utility).
-While some terminals may not accept an arbitrary number
-of tab stops, this implementation will attempt to set tab stops up to the
-right margin of the screen, if the given list happens to be that long.
+POSIX documents no limit on the number of tab stops.
+Other implementations impose one;
+the limit is 20 in PWB/Unix's \fBtabs\fP utility.
+While some terminals may not accept an arbitrary number of tab stops,
+.I \%ncurses
+\fBtabs\fP attempts to set tab stops up to the right margin if the list
+thereof is sufficiently long.
.PP
-The \fIRationale\fP section of the POSIX documentation goes into some
-detail about the ways the committee considered redesigning the
-\fBtabs\fP and \fBtput\fP utilities,
-without proposing an improved solution.
-It comments that
+The \*(``Rationale\*('' section of the Issue 6 \fBtabs\fP reference page
+.\" https://pubs.opengroup.org/onlinepubs/009604499/utilities/tabs.html
+details how the committee considered redesigning the \fBtabs\fP and
+\fBtput\fP utilities,
+without settling on an improved solution.
+It claims that
.RS 5
.PP
no known historical version of tabs supports the capability of setting
arbitrary tab stops.
.RE
.PP
-However, the \fIExplicit Lists\fP described in this manual page
-were implemented in PWB/Unix.
-Those provide the capability of setting abitrary tab stops.
+Nevertheless,
+the feature described in subsection \*(``Explicit Lists\*('' above was
+implemented in PWB/Unix,
+and permits the setting of abitrary tab stops.
.SH SEE ALSO
-\fB@INFOCMP@\fP(1M),
-\fB@TSET@\fP(1),
-\fBcurses\fP(3X),
-\fBterminfo\fP(\*n).
-.PP
-This describes \fBncurses\fP
-version @NCURSES_MAJOR@.@NCURSES_MINOR@ (patch @NCURSES_PATCH@).
+\fB\%@INFOCMP@\fP(1M),
+\fB\%@TSET@\fP(1),
+\fB\%curses\fP(3X),
+\fB\%terminfo\fP(5)
projects / ncurses.git / blobdiff