Tonight I needed to console into a old Cisco 2900 switch to test a couple password related items and it was the first time that I would be using USB to Serial adapter on my Macbook. Previously there had been a lot of issues with the adapter I have, which is a PL-2303, and getting the right drivers installed on Windows 7 64-bit so I was thinking there might not even be drivers available for OSX Lion. After a little research I cam across an article that purehate had written on QD however after following the instructions in the article the USB to Serial adapter still was not working. Below is information on installing newer drivers that will work on OSX Lion.
I have been asked the question numerous times of what PTS and TTY mean in Linux regarding terminals. People ask because they may be newer to Linux and learning how to view a process list they may actually see a serial connection, SSH connection, or a telnet connection in the process list that might show something like pts/0, pts/2, tty1, or tty2 in the TTY column. Most processes will just have a question mark in this column but if something is connected to an actual terminal then it will list where it is connected in the TTY column of “ps”.
When connecting to a Linux device using a serial port there may be times where that connection becomes stuck open and thus will not provide sane output to the TTY port. This issue can be resolved by killing the PID (Process ID) and letting the serial port process restart.
The serial port connection should be configured in inittab which will allow you to specify various configuration options as well as respawning the process. So when you specify respawn the process will automatically restart if it is no longer running as will be the case if you kill the process off. The inittab entry will look similar to one of the two below examples.
There are numerous applications that will allow you to connect to the serial port of a router, switch, load balancer, or other network device. I found the easiest application to use is the trusty old minicom. Minicom is very plain and has an easy configuration which is why I prefer it.
The man page calls minicom a “friendly serial communicator program”.