Running Linux, 5th Edition - Matthias Kalle Dalheimer [189]
Assuming that you're using the mkfs frontend, you can create a filesystem using this command:
mkfs -t type device
where type is the type of filesystem to create, given in Table 10-1, and device is the device on which to create the filesystem (such as /dev/fd0 for a floppy).
For example, to create an ext2 filesystem on a floppy (it does not make much sense to use journaling on a floppy disk, which is why we don't use ext3 here), you use this command:
mkfs -t ext2 /dev/fd0
You could create an MS-DOS floppy using -t msdos instead.
We can now mount the floppy (as described in the previous section), copy files to it, and so forth. Remember to unmount the floppy before removing it from the drive.
Creating a filesystem deletes all data on the corresponding physical device (floppy, hard drive partition, whatever). mkfs usually does not prompt you before creating a filesystem, so be absolutely sure you know what you're doing.
Creating a filesystem on a hard drive partition is done as shown earlier, except that you use the partition name, such as /dev/hda2, as the device. Don't try to create a filesystem on a device such as /dev/hda. This refers to the entire drive, not just a single partition on the drive. You can create partitions using fdisk, as described in "Editing /etc/fstab" in Chapter 2.
You should be especially careful when creating filesystems on hard drive partitions. Be absolutely sure that the device and size arguments are correct. If you enter the wrong device, you could end up destroying the data on your current filesystems, and if you specify the wrong size, you could overwrite data on other partitions. Be sure that size corresponds to the partition size as reported by Linux fdisk.
When creating filesystems on floppies, it's usually best to do a low-level format first. This lays down the sector and track information on the floppy so that its size can be automatically detected using the devices /dev/fd0 or /dev/fd1. One way to do a low-level format is with the MS-DOS FORMAT command; another way is with the Linux program fdformat. (Debian users should use superformat instead.) For example, to format the floppy in the first floppy drive, use the command
rutabaga# fdformat /dev/fd0
Double-sided, 80 tracks, 18 sec/track. Total capacity 1440 kB.
Formatting ... done
Verifying ... done
Using the -n option with fdformat will skip the verification step.
Each filesystem-specific version of mkfs supports several options you might find useful. Most types support the -c option, which causes the physical media to be checked for bad blocks while creating the filesystem. If bad blocks are found, they are marked and avoided when writing data to the filesystem. In order to use these type-specific options, include them after the -t type option to mkfs, as follows:
mkfs -t type -cdevice blocks
To determine what options are available, see the manual page for the type-specific version of mkfs. (For example, for the Second Extended filesystem, see mke2fs.)
You may not have all available type-specific versions of mkfs installed. If this is the case, mkfs will fail when you try to create a filesystem of a type for which you have no mkfs. If you run into trouble using mkfs, it's possible that Linux is having problems accessing the physical device. In the case of a floppy, this might just mean a bad floppy. In the case of a hard drive, it could be more serious; for example, the disk device driver in the kernel might be having problems reading your drive. This could be a hardware problem or a simple matter of your drive geometry being specified incorrectly. See the manual pages for the various versions of mkfs, and read the sections