What is the proper way to get a list of all available serial ports/devices on a Linux system? In other words, when I iterate over all devices in /dev/, how do I tell which ones are serial ports in the classic way, that is, those usually supporting baud rates and flow control? The solution would be coded in C. I ask because I am using a third-party library that does this clearly wrong: It appears to only iterate over /dev/ttyS*.
The problem is that there are, for instance, serial ports over USB (provided by USB-RS232 adapters), and those are listed under /dev/ttyUSB*. And reading the, I get the idea that there'll be other name spaces as well, as time comes. So I need to find the official way to detect serial devices. The problem is that none appears to be documented, or I can't find it. Chhedlyaa taara chhedlyaa bhawraa marathi mp3 songs download.
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I imagine one way would be to open all files from /dev/tty* and call a specific ioctl() on them that is only available on serial devices. Would that be a good solution, though? Update hrickards suggested to look at the source for 'setserial'.
Its code does exactly what I had in mind: First, it opens a device with: fd = open (path, O_RDWR| O_NONBLOCK) Then it invokes: ioctl (fd, TIOCGSERIAL, &serinfo) If that call returns no error, then it's a serial device, apparently. I found similar code in, which suggested to also add the O_NOCTTY option. There is one problem with this approach, though: When I tested this code on BSD Unix (that is, Mac OS X), it worked as well. However, serial devices that are provided through Bluetooth cause the system (driver) to try to connect to the Bluetooth device, which takes a while before it'll return with a timeout error. This is caused by just opening the device.
And I can imagine that similar things can happen on Linux as well - ideally, I should not need to open the device to figure out its type. I wonder if there's also a way to invoke ioctl functions without an open, or open a device in a way that it does not cause connections to be made? What should I do? The /sys filesystem should contain plenty information for your quest. My system (2.6.32-40-generic #87-Ubuntu) suggests: /sys/class/tty Which gives you descriptions of all TTY devices known to the system.
In recent kernels (not sure since when) you can list the contents of /dev/serial to get a list of the serial ports on your system. They are actually symlinks pointing to the correct /dev/ node: flu0@laptop:~$ ls /dev/serial/ total 0 drwxr-xr-x 2 root root 60 2011-07-20 17:12 by-id/ drwxr-xr-x 2 root root 60 2011-07-20 17:12 by-path/ flu0@laptop:~$ ls /dev/serial/by-id/ total 0 lrwxrwxrwx 1 root root 13 2011-07-20 17:12 usb-Prolific_Technology_Inc._USB-Serial_Controller-if00-port0 ->././ttyUSB0 flu0@laptop:~$ ls /dev/serial/by-path/ total 0 lrwxrwxrwx 1 root root 13 2011-07-20 17:12 pci-0000:00:0b.0-usb-0:3:1.0-port0 ->././ttyUSB0 This is a USB-Serial adapter, as you can see. Note that when there are no serial ports on the system, the /dev/serial/ directory does not exists. Hope this helps:).
I think I found the answer in my kernel source documentation: /usr/src/linux-2.6.37-rc3/Documentation/filesystems/proc.txt 1.7 TTY info in /proc/tty ------------------------- Information about the available and actually used tty's can be found in the directory /proc/tty.You'll find entries for drivers and line disciplines in this directory, as shown in Table 1-11. Table 1-11: Files in /proc/tty.......... File Content drivers list of drivers and their usage ldiscs registered line disciplines driver/serial usage statistic and status of single tty lines.......... To see which tty's are currently in use, you can simply look into the file /proc/tty/drivers: > cat /proc/tty/drivers pty_slave /dev/pts 136 0-255 pty:slave pty_master /dev/ptm 128 0-255 pty:master pty_slave /dev/ttyp 3 0-255 pty:slave pty_master /dev/pty 2 0-255 pty:master serial /dev/cua 5 64-67 serial:callout serial /dev/ttyS 4 64-67 serial /dev/tty0 /dev/tty0 4 0 system:vtmaster /dev/ptmx /dev/ptmx 5 2 system /dev/console /dev/console 5 1 system:console /dev/tty /dev/tty 5 0 system:/dev/tty unknown /dev/tty 4 1-63 console Here is a link to this file. I looked at the code and it has the flaw I explain in my question at the end as it has to open the device, which may already lead to a connection attempt - which in turn is not good. But then, maybe Linux drivers are smarter than current OSX driver when it comes to bluetooth support, as they won't open a connection right away? Maybe I should start a new question to clarify that specifically.
If it turns out that that's fine, then I can accept your answer here as well. – May 15 '10 at 8:40. My approach via group dialout to get every tty with user 'dialout' ls -l /dev/tty*| grep 'dialout' to only get its folder ls -l /dev/tty*| grep 'dialout'| rev| cut -d ' ' -f1| rev easy listen to the tty output e.g.