ext4 – How to Delete a File Named ‘filen/ame’ with Slash on ext4 Filesystem in debugfs

debugfsext4slash

Playing with e2fsprogs debugfs, by change/accident, a file named filen/ame was created. Obviously the forward slash character / serves as the special separator character in pathnames.

Still using debugfs I wanted to remove the file named filen/ame, but I had little success, since the / character is not interpreted as part of the filename?

Does debugfs provide a way to remove this file containing the slash? If so how?

I used:

cd /tmp
echo "content" > contentfile
dd if=/dev/zero of=/tmp/ext4fs bs=1M count=50
mkfs.ext4 /tmp/ext4fs
debugfs -w -R "write /tmp/contentfile filen/ame" /tmp/ext4fs
debugfs -w -R "ls" /tmp/ext4fs

which outputs:

debugfs 1.43.4 (31-Jan-2017)
 2  (12) .    2  (12) ..    11  (20) lost+found    12  (980) filen/ame

I tried the following to remove the filen/ame file:

debugfs -w -R "rm filen/ame" /tmp/ext4fs

but this did not work and only produced:

debugfs 1.43.4 (31-Jan-2017)
rm: File not found by ext2_lookup while trying to resolve filename

Apart from changing the content of the directory node manually, is there a way to remove the file using debugfs ?

Best Answer

If you want a fix and are not just trying out debugfs, you can have fsck do the work for you. Mark the filesystem as dirty and run fsck -y to get the filename changed:

$ debugfs -w -R "dirty" /tmp/ext4fs
$ fsck -y /tmp/ext4fs
 ...
/tmp/ext4fs was not cleanly unmounted, check forced.
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Entry 'filen/ame' in / (2) has illegal characters in its name.
Fix? yes
 ...
$ debugfs -w -R "ls" /tmp/ext4fs
2  (12) .    2  (12) ..    11  (20) lost+found    12  (980) filen.ame
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