Two main Unix tools for command line interfaces over serial ports are cu and minicom. I like the latter, my friend Dave likes the former. This article has tricks for using them.
cu can be sorta broken connecting to serial dev when cu installed without the uucp pkg. There needs to be a minimal /etc/uucp/port file in order for cu to be happy. Quick fix: create /etc/uucp/port as follows:
# # Description for the TCP port - pretty trivial. DON'T DELETE. # port TCP type tcp
Minicom was originally designed for acoustic modems, and there are several things that are still in there.
For one thing, it wants to initialize the modem by sending some strings to it when started up. Obviously, this is not good when using it for a connection to your network switch. The -o options stops that.
Additionally, I tend to use USB to Serial Port devices, so I have to explicitly tell minicom what port to use when I start up. Generally, this is /dev/ttyUSB0, and I use the -D parameter to set this.
My normal startup command is
minicom -o -D /dev/ttyUSB0
One of the reasons I like minicom is it is a clean, full screen interface. However, it has tons of options, all accessed as ^a-?, where ? is the specific option you want to execute. ^a-t brings up a menu of options.