X-Git-Url: http://ncurses.scripts.mit.edu/?p=ncurses.git;a=blobdiff_plain;f=doc%2Fhtml%2Fman%2Ftabs.1.html;h=4355d49981425ec4dce3554afe4b9fe124cc0a6e;hp=eef270d8ce7246fe42a2a26ed1c91427ba81f6ce;hb=d30f99439fcc8d4bb4c38e5c4afb4f6555fc6ad4;hpb=02c4e383be9337e73a0e75844dfd1047745adb28 diff --git a/doc/html/man/tabs.1.html b/doc/html/man/tabs.1.html index eef270d8..4355d499 100644 --- a/doc/html/man/tabs.1.html +++ b/doc/html/man/tabs.1.html @@ -1,6 +1,7 @@ @@ -34,7 +35,7 @@ tabs 1 - + @@ -62,38 +63,51 @@ stty tab0 Like clear(1), tabs writes to the standard output. You can redirect - the standard output to a file (which prevents tabs from actually chang- - ing the tabstops), and later cat the file to the screen, setting tab- - stops at that point. + the standard output to a file (which prevents tabs from actually + changing the tabstops), and later cat the file to the screen, setting + tabstops at that point. + + These are hardware tabs, which cannot be queried rapidly by + applications running in the terminal, if at all. Curses and other + full-screen applications may use hardware tabs in optimizing their + output to the terminal. If the hardware tabstops differ from the + information in the terminal database, the result is unpredictable. + Before running curses programs, you should either reset tab-stops to + the standard interval + + tabs -8 + + or use the reset program, since the normal initialization sequences do + not ensure that tab-stops are reset.

OPTIONS

General Options

        -Tname
-            Tell  tabs  which  terminal  type  to  use.  If this option is not
-            given, tabs will use the $TERM environment variable.  If  that  is
+            Tell tabs which terminal type to  use.   If  this  option  is  not
+            given,  tabs  will use the $TERM environment variable.  If that is
             not set, it will use the ansi+tabs entry.
 
-       -d   The  debugging  option  shows  a  ruler line, followed by two data
-            lines.  The first data line shows the  expected  tab-stops  marked
-            with  asterisks.  The second data line shows the actual tab-stops,
+       -d   The debugging option shows a ruler  line,  followed  by  two  data
+            lines.   The  first  data line shows the expected tab-stops marked
+            with asterisks.  The second data line shows the actual  tab-stops,
             marked with asterisks.
 
-       -n   This option tells tabs to check the options and run any  debugging
+       -n   This  option tells tabs to check the options and run any debugging
             option, but not to modify the terminal settings.
 
        -V   reports the version of ncurses which was used in this program, and
             exits.
 
        The tabs program processes a single list of tab stops.  The last option
-       to  be  processed  which  defines a list is the one that determines the
+       to be processed which defines a list is the  one  that  determines  the
        list to be processed.

Implicit Lists

-       Use a single number as an option, e.g., "-5" to set tabs at  the  given
-       interval  (in  this case 1, 6, 11, 16, 21, etc.).  Tabs are repeated up
+       Use  a  single number as an option, e.g., "-5" to set tabs at the given
+       interval (in this case 1, 6, 11, 16, 21, etc.).  Tabs are  repeated  up
        to the right margin of the screen.
 
        Use "-0" to clear all tabs.
@@ -102,15 +116,15 @@

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 exam-
-       ple,
+       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,
 
            tabs 1,6,11,16,21
            tabs 1 6 11 16 21
 
-       Use  a  "+"  to treat a number as an increment relative to the previous
+       Use a "+" to treat a number as an increment relative  to  the  previous
        value, e.g.,
 
            tabs 1,+5,+5,+5,+5
@@ -141,12 +155,13 @@

PORTABILITY

-       IEEE  Std  1003.1/The  Open  Group    Base   Specifications   Issue   7
+       IEEE   Std   1003.1/The   Open   Group   Base  Specifications  Issue  7
        (POSIX.1-2008) describes a tabs utility.  However
 
-       o   This  standard describes a +m option, to set a terminal's left-mar-
-           gin.  Very few of the entries in the terminal database provide this
-           capability.
+       o   This standard describes a +m option,  to  set  a  terminal's  left-
+           margin.   Very  few of the entries in the terminal database provide
+           the  smgl   (set_left_margin)   or   smglp   (set_left_margin_parm)
+           capability needed to support the feature.
 
        o   There  is no counterpart in X/Open Curses Issue 7 for this utility,
            unlike tput(1).
@@ -154,17 +169,45 @@
        The -d (debug) and -n (no-op) options are extensions  not  provided  by
        other implementations.
 
-       Documentation for other implementations states that there is a limit on
-       the number of tab stops.  While some terminals may not accept an  arbi-
-       trary  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.
+       A  tabs  utility  appeared in PWB/Unix 1.0 (1977).  There was a reduced
+       version of the tabs 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).  That option is not documented by POSIX.
+
+       The PWB/Unix tabs utility, which was included  in  System  III  (1980),
+       used  built-in  tables  rather than the terminal database, to support a
+       half-dozen terminal types.  It also had built-in logic to  support  the
+       left-margin,  as  well as a feature for copying the tab settings from a
+       file.
+
+       Later versions of Unix, e.g., SVr4,  added  support  for  the  terminal
+       database,   but  kept  the  tables,  as  a  fallback.   In  an  earlier
+       development effort, the tab-stop initialization provided by tset (1982)
+       and incorporated into tput uses the terminal database,
+
+       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 tabs 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.
+
+       The Rationale section of the POSIX documentation goes into some  detail
+       about  the  ways the committee considered redesigning the tabs and tput
+       utilities, without proposing an improved solution.  It comments that
+
+            no known historical version of tabs  supports  the  capability  of
+            setting arbitrary tab stops.
+
+       However,  the  Explicit  Lists  described  in  this  manual  page  were
+       implemented in PWB/Unix.   Those  provide  the  capability  of  setting
+       abitrary tab stops.

SEE ALSO

-       tset(1), infocmp(1m), curses(3x), terminfo(5).
+       infocmp(1m), tset(1), curses(3x), terminfo(5).
 
-       This describes ncurses version 6.1 (patch 20180407).
+       This describes ncurses version 6.2 (patch 20210403).