Rework the color option to support setting ANSI color code values
ranging from 0..255 or "none" for no color or "list" to print a list of
available ANSI colors codes.
Also, disables color when piping.
This feature allows an external program to inject output into and
listen to input from a serial port via a Unix domain socket (path
specified via the -S/--socket command line flag, or the socket
config file option) while tio is running. This is useful for ad-hoc
scripting of serial port interactions while still permitting manual
control. Since many serial devices (at least on Linux) get confused
when opened by multiple processes, and most commands do not know
how to correctly open a serial device, this allows a more convenient
usage model than directly writing to the device node from an external
program.
Any input from clients connected to the socket is sent on the serial
port as if entered at the terminal where tio is running (except that
ctrl-t sequences are not recognized), and any input from the serial
port is multiplexed to the terminal and all connected clients.
Sockets remain open while the serial port is disconnected, and writes
will block.
Example usage 1 (issue a command):
echo command | nc -UN /path/to/socket > /dev/null
Example usage 2 (use the expect command to script an interaction):
#!/usr/bin/expect -f
set timeout -1
log_user 0
spawn nc -UN /path/to/socket
set uart $spawn_id
send -i $uart "command1\n"
expect -i $uart "prompt> "
send -i $uart "command2\n"
expect -i $uart "prompt> "
Renamed to "tio" because it is shorter and this new name also more
precisely reflects what the program is - a simple TTY terminal I/O
application.
"tio" can be considered short for terminal I/O or TTY I/O or a
combination of the two, whichever you prefer.
Also, wanted to avoid naming conflicts with other projects.
