Formatting a Linux partition

eldiener · 06-17-2018, 07:23 AM

I have the need to be able to programatically format a thumb drive having a single Linux partition on it using C/C++. What function call(s) do I need to make in order to get this done ?

I want to format the partition using a default partition type of my choosing if the partition has not yet been formatted. Otherwise I want to reformat the partition with the same partition type it already has. I know how to programatically mount or unmount the thumb drive to a path. What I do not know are the details of the functionality for formatting or reformatting the partition of the thumb drive.

Any help in this area would be welcome. I am an experienced C++ programmer, but have not dealt with this functionality on Linux before.

NevemTeve · 06-17-2018, 08:01 AM

As a start, you could use popen(3) on fdisk(8):

Code:

fdisk -o Device,Id,Type -l /dev/sda 2>/dev/null | grep '^/'
/dev/sda1   7 HPFS/NTFS/exFAT
/dev/sda2   7 HPFS/NTFS/exFAT
/dev/sda3   5 Extended
/dev/sda4  12 Compaq diagnostics
/dev/sda5  82 Linux swap / Solaris
/dev/sda6  83 Linux
/dev/sda7  83 Linux

rtmistler · 06-17-2018, 07:06 PM

Best way to learn how this is done via programming is to read the source code.

From the manual page for mkfs as well as fdisk:

Quote:

The mkfs/fdisk command is part of the util-linux package and is available from https://www.kernel.org/pub/linux/utils/util-linux/.

eldiener · 06-18-2018, 11:15 AM

Quote:

Originally Posted by NevemTeve

As a start, you could use popen(3) on fdisk(8):

Code:

fdisk -o Device,Id,Type -l /dev/sda 2>/dev/null | grep '^/'
/dev/sda1   7 HPFS/NTFS/exFAT
/dev/sda2   7 HPFS/NTFS/exFAT
/dev/sda3   5 Extended
/dev/sda4  12 Compaq diagnostics
/dev/sda5  82 Linux swap / Solaris
/dev/sda6  83 Linux
/dev/sda7  83 Linux

What does piping the results of an fdisk call get me ? I already know the device designation I need to format. Do you mean to say that reading the output from fdisk is the standard way of determing what filesystem is on a partition rather than calling some Linux API function which gives me that information ?

eldiener · 06-18-2018, 11:18 AM

Quote:

Originally Posted by rtmistler

Best way to learn how this is done via programming is to read the source code.

From the manual page for mkfs as well as fdisk:

Thanks for the link ! I was hoping to not have to read source code to understand what to do but to be pointed to some API(s) that do what I want.