How to detect insertion/removal of flash card in usb reader?
Linux - HardwareThis forum is for Hardware issues.
Having trouble installing a piece of hardware? Want to know if that peripheral is compatible with Linux?
Welcome to LinuxQuestions.org, a friendly and active Linux Community.
You are currently viewing LQ as a guest. By joining our community you will have the ability to post topics, receive our newsletter, use the advanced search, subscribe to threads and access many other special features. Registration is quick, simple and absolutely free. Join our community today!
Note that registered members see fewer ads, and ContentLink is completely disabled once you log in.
If you have any problems with the registration process or your account login, please contact us. If you need to reset your password, click here.
Having a problem logging in? Please visit this page to clear all LQ-related cookies.
Introduction to Linux - A Hands on Guide
This guide was created as an overview of the Linux Operating System, geared toward new users as an exploration tour and getting started guide, with exercises at the end of each chapter.
For more advanced trainees it can be a desktop reference, and a collection of the base knowledge needed to proceed with system and network administration. This book contains many real life examples derived from the author's experience as a Linux system and network administrator, trainer and consultant. They hope these examples will help you to get a better understanding of the Linux system and that you feel encouraged to try out things on your own.
Click Here to receive this Complete Guide absolutely free.
Nothing appears in my log, which is set up to record *.info and above. Seems like an unfortunate way to determine whether a card is in the reader anyway. Is there something analogous to hotplug that will allow a script to be called on card insertion/removal, or perhaps a flag that shows up somewhere under /proc?
My initial query remains unresolved, so I'll try and rephrase it:
I have a USB flash card reader as described above. Is there a way for me to detect when a flash card has been inserted into it? (Note that I do *not* want to detect whether the reader itself is connected to the PC - I know how to do that).
The links above mainly concentrate on how to identify the right SCSI device and mount it.
I worked it out for myself in the end. The SCSI kernel driver returns a "no medium" code when an open() call is made and removable media (e.g. flash card) is not present. So all I need to do is make an open() call, and see what the return code is. I want to work at the bash level, so rather than writing c code to do this, I just used sg_dd from the sg3_utils suite, which does calls open - I grep out the 'no media' error. Of course, this works whether the reader has been mounted or not.
I am a newbie in Linux. I want to detect Usb flash drive in C whether polling or not. I thing I found a solution in this message:
Originally Posted by logularjason
...I worked it out for myself in the end. The SCSI kernel driver returns a "no medium" code when an open() call is made and removable media (e.g. flash card) is not present. So all I need to do is make an open() call, and see what the return code is.
However I did not understand that how can I call "open()" in C in order to see the existance of USB flash drive? Could you give an samle code block,please? Thanks.