given file, determine device

JudyL · 02-01-2008, 10:13 AM

Given a fully-qualified file name, say /home/judy/test/data.bin, how can I determine which device (/dev/???) this file is located on? You may safely assume that the device containing the file will be mounted when I'm doing this. I'm looking to do this in C / C++.

Thanks!!
Judy

jailbait · 02-01-2008, 12:25 PM

Quote:

Originally Posted by JudyL

Given a fully-qualified file name, say /home/judy/test/data.bin, how can I determine which device (/dev/???) this file is located on? You may safely assume that the device containing the file will be mounted when I'm doing this. I'm looking to do this in C / C++.

Thanks!!
Judy

The mount table (/etc/mtab) gives you what file systems are mounted and their mount point. So you would compare the directories in your path, /home/judy/test/, against /etc/mtab to see what device data.bin is on.

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Steve Stites

JudyL · 02-01-2008, 12:32 PM

That lists volumes not physical devices i.e. /dev/sda1, but I can always strip the volume number from the volume to get back to the physical drive.

I was hoping for something simple like a command or function call, but I'll parse that mtab file if nothing easier turns up.

Thanks!!
Judy

jrtayloriv · 02-01-2008, 12:34 PM

You are looking for stat.

There is a function in the GNU C library (see man stat.h and man 2 stat and info libc's "Filesystem Interface" section)

There is also a GNU coreutils program called 'stat'(man stat)

--jrtayloriv

JudyL · 02-01-2008, 12:45 PM

Quote:

Originally Posted by jrtayloriv

You are looking for stat.

There is a function in the GNU C library (see man stat.h and man 2 stat and info libc's "Filesystem Interface" section)

There is also a GNU coreutils program called 'stat'(man stat)

--jrtayloriv

stat is definitely it - it identifies the volume and it is easy to backtrack from the volume to the physical device.

Thanks!!
Judy