filters out reverse (and half reverse) line feeds so the output is
in the correct order with only forward and half forward line
feeds, and replaces white-space characters with tabs where possible.
This can be useful in processing the output of
reads from standard input and writes to standard output.
The options are as follows:
Do not output any backspaces, printing only the last character
written to each column position.
Forward half line feeds are permitted (``fine'' mode).
Normally characters printed on a half line boundary are printed
on the following line.
Force unknown control sequences to be passed through unchanged.
will filter out any control sequences from the input other than those
recognized and interpreted by itself, which are listed below.
Output multiple spaces instead of tabs.
Buffer at least
lines in memory.
By default, 128 lines are buffered.
The control sequences for carriage motion that
understands and their decimal values are listed in the following
reverse line feed (escape then 7)
half reverse line feed (escape then 8)
half forward line feed (escape then 9)
moves back one column (8); ignored in the first column
forward line feed (10); also does carriage return
shift to normal character set (15)
shift to alternate character set (14)
moves forward one column (32)
moves forward to next tab stop (9)
reverse line feed (11)
All unrecognized control characters and escape sequences are
keeps track of the character set as characters are read and makes
sure the character set is correct when they are output.
If the input attempts to back up to the last flushed line,
will display a warning message.