Re: specifying tab stops using tabs

[Thomas Dickey]

On Thu, Jun 06, 2013 at 06:19:32PM +0200, Nick Andrik wrote:
> In my system, the documentation of tabs states:
> 
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    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 to the right margin
>        of the screen.
> 
>        Use "-0" to clear all tabs.
> 
>        Use "-8" to set tabs to the standard interval.
...
 
> tabs 1,+5,+5,+5,+5,+5,+5,+5,+5,+5,+5,+5,+5,+5,+5,+5,+5,+5
> ----+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
> *----*----*----*----*----*----*----*----*----*----*----*----*----*----*----*----
> *     *       *       *       *       *       *       *       *       *       
> *       *       *       *       *       *
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

hmm - considering whether I made a mistake in documenting it...

The X/Open documentation is vague in this area, and does not
contain as much detail as Solaris's manpage.  Quoting from that:

     If no tab specification is given, the default value  is  -8,
     that  is,  UNIX system ``standard'' tabs.  The lowest column
     number is 1.  Note:  For tabs, column 1 always refers to the
     leftmost column on a terminal, even one whose column markers
     begin at 0, for example, the DASI 300, DASI 300s,  and  DASI
     450.

but later it contradicts itself (by omitting the case for "1+0*n"):

  Repetitive
     -n        A  repetitive  specification  requests   tabs   at
               columns  1+n,  1+2*n,  etc.,  where n is a single-
               digit decimal number.  Of particular importance is
               the  value  8:   this  represents  the UNIX system
               ``standard'' tab setting, and is the  most  likely
               tab  setting to be found at a terminal. When -0 is
               used, the tab stops are cleared and  no  new  ones
               are set.

Either way, the documentation is more correct than the code.

-- 
Thomas E. Dickey <address@hidden>
http://invisible-island.net
ftp://invisible-island.net

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