tabs — set tabs on a terminal
sets the tab stops on the user's terminal
according to the tab specification
after clearing any previous settings.
The user's terminal must have remotely-settable hardware tabs.
If you are using a non-HP terminal, you should keep in mind that
behavior will vary for some tab settings.
Four types of tab specification are accepted for
arbitrary, and file.
is given, the default value is
The lowest column number is 1.
Note that for
column 1 always refers to the left-most column on a terminal,
even one whose column markers begin at 0.
Gives the name of one of a set of ``canned'' tabs.
and their meanings are as follows:
S/370, first format
S/370, second format
compact format (columns 1-6 omitted).
Using this code, the first typed character corresponds to card column 7,
one space gets you to column 8, and a tab reaches column 12.
Files using this tab setup should have
specify a format specification file as defined by
should have the following format specification:
compact format (columns 1-6 omitted), with more tabs than
This is the recommended format for
The appropriate format specification is:
In addition to these ``canned'' formats, three other types exist:
A repetitive specification requests tabs at columns
Of particular importance is the value
this represents the
``standard'' tab setting,
and is the most likely tab setting to be found at a terminal.
Another special case is the value
implying no tabs at all.
The arbitrary format permits the user to type any
chosen set of numbers, separated by commas, in ascending order.
Up to 40 numbers are allowed.
If any number (except the first one) is preceded by a plus sign,
it is taken as an increment to be added to the previous value.
Thus, the tab lists 1,10,20,30 and 1,10,+10,+10 are considered identical.
If the name of a file is given,
reads the first line of the file, searching for a format specification.
If it finds one there, it sets the tab stops according to it, otherwise it
sets them as
This type of specification can be used
to ensure that a tabbed file is printed with correct tab settings,
and is suitable for use with the
Any of the following can be used also;
if a given option occurs more than once,
the last value given takes effect:
usually needs to know the type of terminal in order to set tabs
and always needs to know the type to set margins.
is a name listed in
option is supplied,
searches for the
value in the
is not defined in the environment,
tries a sequence that will work for many terminals.
The margin argument can be used for some terminals.
It causes all tabs to be moved over
columns by making column
the left margin.
is given without a value of
the value assumed is 10.
The normal (left-most) margin on most terminals is obtained by
The margin for most terminals is reset only when the
option is given explicitly.
Tab and margin setting is performed via the standard output.
determines the interpretation of text within file
as single- and/or multi-byte characters.
determines the language in which messages are displayed.
is not specified in the environment or is set to
the empty string, the value of
is used as a default for each
unspecified or empty variable.
is not specified or is set to the empty string, a default of "C" (see
is used instead of
If any internationalization variable contains an invalid setting,
behaves as if all internationalization variables are set to "C".
International Code Set Support
Single- and multi-byte character code sets are supported.
- illegal tabs
Arbitrary tabs are ordered incorrectly.
- illegal increment
A zero or missing increment found in an arbitrary specification.
- unknown tab code
A ``canned'' code cannot be found.
- can't open
option was used and file cannot be opened.
- file indirection
option was used and the specification in that file
points to yet another file.
Indirection of this form is not permitted.
There is no consistency among different terminals
regarding ways of clearing tabs and setting the left margin.
It is generally impossible to usefully change the left margin
without also setting tabs.
clears only 20 tabs (on terminals requiring a long sequence),
but is willing to set 64.
tabs: SVID2, SVID3, XPG2, XPG3, XPG4