Re: [PATCH, RFC] btrfs-progs: require mkfs -f force option to overwrite filesystem or partition table

[Martin Steigerwald <Martin@lichtvoll.de>]

Am Dienstag, 26. Februar 2013 schrieb Goffredo Baroncelli:
> > And I teach not to in my trainings as well.
> >
> > 
> >
> > Everyone who uses rm -rf by default even just for deleting a single
> > file does  it as long as he or she deleted his / her home directory or
> > something.
> 
> Unfortunately the "rm -rf" is a different case. Removing a directory is
> a common case. We should not be forced to use the -f for common case. A
> '-f' flag should be used only in "uncommon" case (like *re*format a disk
> or a test-suite)...
> 
> However I think that '-f' is good for mkfs.btrfs.

I don´t get you on this one:

artin@merkaba:~/Zeit> export LANG=C
martin@merkaba:~/Zeit> mkdir test
martin@merkaba:~/Zeit> rm test
rm: cannot remove 'test': Is a directory
martin@merkaba:~/Zeit#1> rm -f test
rm: cannot remove 'test': Is a directory
martin@merkaba:~/Zeit#1> rm -r test
martin@merkaba:~/Zeit> mkdir test
martin@merkaba:~/Zeit> rmdir test
martin@merkaba:~/Zeit>

So you do not need -f to remove a directory, but either rm -r or rmdir (if 
its empty).

I think that special casing deleting empty directories with rmdir command 
doesn´t make much sense. The most important distinction there IMHO is to 
recurse or not to recurse. Thus I would let rm also delete empty directories 
and remove rmdir altogether or alias it to rm (without -r!). Thats how it 
was done on AmigaOS delete command. Delete would delete files and empty 
dirs, and recurse only if ALL option was given.

rm -f doesn´t work anyway if parent directory has write permission removed:

martin@merkaba:~/Zeit> mkdir -p test/test
martin@merkaba:~/Zeit> chmod a-w test
martin@merkaba:~/Zeit> cd test
martin@merkaba:~/Zeit> rm -r test
rm: descend into write-protected directory 'test'? y
rm: cannot remove 'test/test': Permission denied
martin@merkaba:~/Zeit> rm -rf test
rm: cannot remove 'test/test': Permission denied

       -f, --force
              ignore nonexistent files and arguments, never prompt



Only in the case the directory itself is write-protected rm -f makes the 
prompt go away:

martin@merkaba:~/Zeit> mkdir test
martin@merkaba:~/Zeit> chmod a-w test
martin@merkaba:~/Zeit> rm -r test
rm: remove write-protected directory 'test'? y
martin@merkaba:~/Zeit> mkdir -m a-w test
martin@merkaba:~/Zeit> ls -ld test
dr-xr-xr-x 1 martin martin 0 Feb 26 22:12 test
martin@merkaba:~/Zeit> rm -rf test

But on skipping write protection -f is justified I think.

But more so since this is a empty directory and the parent directory has 
write protection, rmdir will remove it without -f (which it doesn´t support 
anyway):

martin@merkaba:~/Zeit> mkdir -m a-w test
martin@merkaba:~/Zeit> rmdir test
martin@merkaba:~/Zeit> 

Thanks,
-- 
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
GPG: 03B0 0D6C 0040 0710 4AFA  B82F 991B EAAC A599 84C7