tabs[tabspec] [options]
Set terminal tab stops according to tabspec.
The default tabspec, -8, gives the standard UNIX tab settings.
Specify tabspec as a predefined set
of tab stops for particular languages, for example:
a (IBM assembler), c (COBOL), 
f (FORTRAN), p (PL/1), 
s (SNOBOL), and u (UNIVAC).
tabspec can also be a repeated number, arbitrary numbers,
or called from a file.  
nRepeat tab every n columns (e.g., 1+n, 1+2*n, etc.).
n1,n2,...Arbitrary ascending values.  If n is preceded by +,
it is added (i.e., tab is relative to previous position).
1, 10, 16, 36, 72.
1, 10, 16, 40, 72.
1, 8, 12, 16, 20, 55.
1, 6, 10, 14, 49.
1, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62, 67.
1, 7, 11, 15, 19, 23.
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61.
1, 10, 55.
1, 12, 20, 44.
fileRead first line of file for tabs.
nSet left margin to n (default is 10).
typeSet terminal type (default is TERM).