this is extremely inefficient, instead write them all down at the
beginning.
The correct sequence to switch colours off is to first use 'op' if
it exists, otherwise use 'oc'. If neither of these exist then we
shouldn't be doing colour with this terminal.
Reviewed by: ache
to manage the ANSI colour sequences. Colour support is disabled
unless the TERM environment variable references a valid termcap.
* Allow optional compilation of the colour support in the Makefile,
defaulting to yes. This allows us to switch it off for fixit
floppies and other mediums where space is an issue and the extra
bloat of statically linking with ncurses isn't acceptable.
* Display a warning if colour is requested with '-G' but support
for it isn't compiled in.
It is not switched on by default and must be enabled with the -G
flag. When using ls -G the output behaviour is modified with ANSI
colour sequences wrapped around filenames to help distinguish file
types. (Colours can be redefined in the LSCOLORS environment
variable as described in the manual page.)
Colour support is silently disabled (if switched on) if stdout
isn't a tty.
Based on: asami's colorls port.
PR: bin/18900 && ports/18616.
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.
