Reformatting a USB drive
When inserted into a USB slot, USB drives, should show up in the output of /mount or in /proc/mounts.
The filesystem type will show up also in this output. USB drives tend to be formatted for Windows (ntfs via fuseblk)
If you want to reformat a USB drive (reformatting involves deleting all pre-existing data on the drive), firstly you should become root then issue a umount command on the disk device (typically under /dev/sdb1 if you're on a regular desktop with one drive, but take care to identify the USB drive on a multi-HDD machine) but leave the USB drive physically attached to the computer.
Create a new filesystem on the USB device with mkfs while specifying the filesystem type with option -t and the former mount point as an argument. Below is an example of mkfs with a filesystem type of ext4.
[root@band media]# mkfs -t ext4 /dev/sdb1 mke2fs 1.41.12 (17-May-2010) Filesystem label= OS type: Linux Block size=4096 (log=2) Fragment size=4096 (log=2) Stride=0 blocks, Stripe width=0 blocks 265056 inodes, 1058560 blocks 52928 blocks (5.00%) reserved for the super user First data block=0 Maximum filesystem blocks=1086324736 33 block groups 32768 blocks per group, 32768 fragments per group 8032 inodes per group Superblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736 Writing inode tables: done Creating journal (32768 blocks): done Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every 39 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override.
After new filesystem has been created, remove the USB drive then plug it back in again. You should be able to view the new filesystem. Check output of mount and /proc/mounts again.
To create a bootable USB drive
For this example, we'll create a bootable CentOS USB drive.
Firstly, download the .iso file of the OS you want to download. Change directories to the folder that contains your desired OS .iso.
[root@band bwong1]# cd Downloads [root@band Downloads]# ls Benjamin_Wong_RHCSA.pdf email@example.com ccp4-7.0-shelx-linux-x86_64.tar.bz2 CentOS-6.8-x86_64-LiveCD.iso
Secondly, plug in a reformatted USB drive. Use the mount command to see the device name of your USB drive.
[root@band Downloads]# mount *** /dev/sdc on /media/9fff3ec2-8853-4c6a-a6f0-8a1b2491fb80 type ext4 (rw,nosuid,nodev,uhelper=udisks)
Unmount your usb drive prior to writing the ISO onto it.
[root@band Downloads]# umount /dev/sdc
Now, write the .ISO file into the USB drive with the dd command. if stands for input file and of stands for output file. Send your output file to the USB drive's location.
[root@band Downloads]# dd if=CentOS-6.8-x86_64-LiveCD.iso of=/dev/sdc bs=1M 702+0 records in 702+0 records out 736100352 bytes (736 MB) copied, 132.887 s, 5.5 MB/s