Linux – Simulate a USB Device for Automation

driverkernellibusblinuxsimulation

I have to simulate a USB Device for automation and testing purposes (in Linux). Original driver/application for this device uses “libusb” to communicate with it.

I don’t have much experience in Linux and Simulation, after some searching I have understood that I need to write a kernel level driver and an application in user-space to simulate that device. Is this right? If Yes, How can this be done?

Thanks in Advance.

Best Answer

Finally implemented it by modifying "libusb", modified it to send and receive usb transfers from message queue instead of usbfs. Programmed my simulator to create libsub type transfers and send/receive them using message queues as well.

Simulator now interprets the incoming transfers and sends it to a command parser, which sends request/message to automation system using sockets in a specific format. Automation system sends it's instruction by sending to command parser using socket. This socket invokes method specific to each request in simulator, Now simulator forms an appropriate transfer structure and passes to device plugin (via libusb) through message queue.

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Linux – How to change permissions for a folder and its subfolders/files in one step

The other answers are correct, in that chmod -R 755 will set these permissions to all files and subfolders in the tree. But why on earth would you want to? It might make sense for the directories, but why set the execute bit on all the files?

I suspect what you really want to do is set the directories to 755 and either leave the files alone or set them to 644. For this, you can use the find command. For example:

To change all the directories to 755 (drwxr-xr-x):

find /opt/lampp/htdocs -type d -exec chmod 755 {} \;

To change all the files to 644 (-rw-r--r--):

find /opt/lampp/htdocs -type f -exec chmod 644 {} \;

Some splainin': ^{(thanks @tobbez)}

chmod 755 {} specifies the command that will be executed by find for each directory
chmod 644 {} specifies the command that will be executed by find for each file
{} is replaced by the path
; the semicolon tells find that this is the end of the command it's supposed to execute
\; the semicolon is escaped, otherwise it would be interpreted by the shell instead of find

Linux – Accessing Linux /dev/USB as standard files to communicate with USB device

Jim, I don't think you can escape the need to write a driver and just manage to read the USB file in /dev. Because who defines as to what should happen when you do a read() on the USB device file? And who defines what action should be initiated when you invoke sysioctl()? Your driver! In other words, the device files are themselves incapable of anything until they are supported by the underlying drivers. In fact, you can treat the device files to be an abstraction of the underlying driver! So, no driver, no use of device file :(

I suggest you go through the following articles about how to write a driver and also understand the USB internals-

http://www.linux-usb.org/USB-guide/c15.html
http://www.linuxjournal.com/article/4786 ( Slightly outdated )

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Linux – How to change permissions for a folder and its subfolders/files in one step

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