mke2fs -t vfat created an ext2 file system

catkin · 03-23-2010, 07:00 AM

Hello

I wanted to put a label on a USB memory stick's FAT32 file system. mkfs.vfat is not available on my Slackware 13.0 system and slackpkg search mkfs.vfat found nothing. Back in December 09, linuxlover.chaitanya suggested using mke2fs -t vfat in this LQ post. I tried it -- and got a ext2 file system

Code:

root@CW8:~# mke2fs -t vfat -L CHARLES8G /dev/sdc1
[After mounting via Thunar ...]
root@CW8:~# df -hT /dev/sdc1
Filesystem    Type    Size  Used Avail Use% Mounted on
/dev/sdc1     ext2    7.4G   17M  7.0G   1% /media/CHARLES8G

Why did that happen?

Best

Charles

bathory · 03-23-2010, 07:04 AM

Hi,

Why don't you use mkdosfs?

Regards

syg00 · 03-23-2010, 07:12 AM

Quote:

Originally Posted by catkin

Why did that happen?

Because you used mke2fs - and you made an e(xt)2 fs.
No surprise there. Read the manpage before doing anything potentially destructive.

michaelk · 03-23-2010, 07:22 AM

AFAIK there is no valid -t option and mke2fs can not create a vfat filesystem. I am curious if it really did create a vfat filesystem in the other thread.

onebuck · 03-23-2010, 07:36 AM

Hi,

Quote:

excerpt from 'man mke2fs';
NAME
mke2fs - create an ext2/ext3/ext4 filesystem

SYNOPSIS
mke2fs [ -c | -l filename ] [ -b block-size ] [ -f fragment-size ] [ -g blocks-per-group ] [ -G
number-of-groups ] [ -i bytes-per-inode ] [ -I inode-size ] [ -j ] [ -J journal-options ] [ -N
number-of-inodes ] [ -n ] [ -m reserved-blocks-percentage ] [ -o creator-os ] [ -O fea-
ture[,...] ] [ -q ] [ -r fs-revision-level ] [ -E extended-options ] [ -v ] [ -F ] [ -L vol-
ume-label ] [ -M last-mounted-directory ] [ -S ] [ -t fs-type ] [ -T usage-type ] [ -U UUID ] [
-V ] device [ blocks-count ]

mke2fs -O journal_dev [ -b block-size ] [ -L volume-label ] [ -n ] [ -q ] [ -v ] external-jour-
nal [ blocks-count ]

DESCRIPTION
mke2fs is used to create an ext2, ext3, or ext4 filesystem, usually in a disk partition.
device is the special file corresponding to the device (e.g /dev/hdXX). blocks-count is the
number of blocks on the device. If omitted, mke2fs automagically figures the file system size.
If called as mkfs.ext3 a journal is created as if the -j option was specified.

The defaults of the parameters for the newly created filesystem, if not overridden by the
options listed below, are controlled by the /etc/mke2fs.conf configuration file. See the
mke2fs.conf(5) manual page for more details.

Quote:

excerpt from 'man mke2fs';

-t fs-type
Specify the filesystem type (i.e., ext2, ext3, ext4, etc.) that is to be created. If
this option is not specified, mke2fs will pick a default either via how the command was
run (for example, using a name of the form mkfs.ext2, mkfs.ext3, etc.) or via a default
as defined by the /etc/mke2fs.conf(5) file. This option controls which filesystem
options are used by default, based on the fstypes configuration stanza in
/etc/mke2fs.conf(5).

If the -O option is used to explicitly add or remove filesystem options that should be
set in the newly created filesystem, the resulting filesystem may not be supported by
the requested fs-type. (e.g., "mke2fs -t ext3 -O extents /dev/sdXX" will create a
filesystem that is not supported by the ext3 implementation as found in the Linux ker-
nel; and "mke2fs -t ext3 -O ^has_journal /dev/hdXX" will create a filesystem that does
not have a journal and hence will not be supported by the ext3 filesystem code in the
Linux kernel.)

The user would have to modify '/etc/mke2fs.conf' to use alternate FS. Why?

catkin · 03-23-2010, 07:51 AM

Quote:

Originally Posted by bathory

Why don't you use mkdosfs?

Thanks bathory

I did but cfdisk did not show the label created by mkdosfs's -n option. Thunar found it OK, displayed it and used it when creating the temporary mountpoint/directory in /media.

That's why I was looking for an alternative way of creating the label, hoping it might be more widely visible.

catkin · 03-23-2010, 07:52 AM

Quote:

Originally Posted by syg00

Because you used mke2fs - and you made an e(xt)2 fs.
No surprise there. Read the manpage before doing anything potentially destructive.

Thanks for your concern, syg00

I had read the man page, it documented the -t option and the device held no data.

catkin · 03-23-2010, 07:58 AM

Quote:

Originally Posted by onebuck

The user would have to modify '/etc/mke2fs.conf' to use alternate FS. Why?

I wasn't surprised that it didn't work (was half-hopeful, based on the December thread's advice given and reported success -- and that the ext2 utilities work on ext3 and ext4) but was surprised that it did not halt on error when an invalid -t option value was given.