[TUHS] rm command

Michael Kjörling michael at kjorling.se
Sun Apr 29 02:33:51 AEST 2018

On 27 Apr 2018 11:17 -0700, from pete at nomadlogic.org (Pete Wright):
>>>    On my FreeBSD server:
>>>     % ls -l /bin/ps
>>>     -r-xr-xr-x  1 root  wheel  35640 Oct 15  2017 /bin/ps
>>>    On my crappy MacBook:
>>>     % ls -l /bin/ps
>>>     -rwsr-xr-x  1 root  wheel  51200 Jul 15  2017 /bin/ps
>> Debian 9:
>> nicci at jesustheasus:~$ ls -l $(which ps)
>> -rwxr-xr-x 1 root root 129336 Nov 22  2016 /bin/ps
>> Debian 8 kFreeBSD:
>> [usotsuki at licca ~]$ ls -l $(which ps)
>> -rwxr-xr-x 1 root root 93088 Mar  6  2015 /bin/ps

Debian 7 is the same, except /bin/ps is 93120 bytes there.

> interesting how the gnu userland marks ps as owner-writable, not
> sure it matters, but interesting...

That's more likely the package manager, or the packaging done by the
package maintainer, than it is anything about GNU per se.

I've got a gazillion 0755 0:0 binaries on my system. In fact, running
`ls -l /usr/bin | grep -v '^.rwx'` on my desktop Debian box returns
only a handful of hits, all of which are u=rws and a few of which are

If you're root enough to take advantage of the owner-writable bit on a
file owned by root, then you're root enough to make quite a mess even
if they were mode 0555 or even 0111.

If you want weird, then tell me why on Earth /bin/ping _really_ needs
to be setuid root on Linux (has no one heard of capabilities?), or why
/bin/fusermount is, of all modes they could choose from, `-rwsr-xr--`.

Michael Kjörling • https://michael.kjorling.semichael at kjorling.se
  “The most dangerous thought that you can have as a creative person
              is to think you know what you’re doing.” (Bret Victor)

More information about the TUHS mailing list