The Linux Serial HOWTO

by Greg Hankins, greg.hankins@cc.gatech.edu

1. Introduction

• 1.1 Copyright
• 1.2 Other sources of information
• 1.3 New versions of this document
• 1.4 Feedback
• 1.5 Disclaimer

2. Supported serial hardware

• 2.1 Multiport serial boards (with 16450/16550A UARTs)
• 2.2 Intelligent multiport serial boards

3. What are the names of the serial ports?

• 3.1 Major and minor device numbers of serial devices in /dev

4. What is getty?

• 4.1 About getty_ps
• 4.2 About mgetty
• 4.3 About agetty

5. What is setserial?

6. What is setserial?

• 6.1 Hardware requirements
• 6.2 Talking to your modem
• 6.3 Dial out modem configuration
• 6.4 Hardware flow control

7. How do I dial in and out with my modem using getty_ps?

• 7.1 Dial in and out modem configuration
• 7.2 Installing getty_ps
• 7.3 Setting up uugetty
• 7.4 Customizing uugetty
• 7.5 US Robotics Notes
• 7.6 Supra Notes

8. How do I set up a terminal connected to my PC?

• 8.1 Hardware requirements
• 8.2 Setting up getty
• 8.3 Notes on setting up a PC as a terminal

9. Notes on setting up a PC as a terminal

• 9.1 Choosing serial device interrupts
• 9.2 Setting serial device addresses

10. Setting serial device addresses

11. Setting serial device addresses

12. Serial Tips

• 12.1 kermit and zmodem
• 12.2 Setting terminal types automagically
• 12.3 Color ls on serial connections
• 12.4 Printing to a printer connected to a terminal
• 12.5 Can Linux configure the serial devices automagically?

13. Linux FTP sites

14. One step further...

• 14.1 What are lock files?
• 14.2 ``baud'' vs. ``bps''
• 14.3 ``baud'' vs. ``bps''
• 14.4 What's the real difference between the /dev/cuaN and

15. Troubleshooting

• 15.1 I keep getting ``line NNN of inittab invalid''.
• 15.2 When I try to dial out, it says ``/dev/cuaN: Device or resource busy''.
• 15.3 I keep getting ``Id SN respawning too fast: disabled for 5 minutes''.
• 15.4 Serial devices are slow or serial devices can only send in one direction.
• 15.5 My modem is hosed after someone hangs up, or uugetty doesn't
• 15.6 I have my terminal connected to my PC, but after I type in a login name,
• 15.7 At high speeds, my modem loses data.
• 15.8 On startup, Linux doesn't report the serial devices the way I have
• 15.9 rz and/or sz don't work when I call my Linux box on my modem.
• 15.10 My screen is printing funny looking characters.
• 15.11 getty or uugetty still doesn't work.

16. Contributions