[TUHS] rm command

Dave Horsfall dave at horsfall.org
Sat Apr 28 02:26:16 AEST 2018

On Wed, 25 Apr 2018, Noel Chiappa wrote:

> On early PDP-11 Unixes, 'rm' is an ordinary program, and 'rmdir' is 
> setuid-root, since it has to do special magic (writing into directory 
> files, etc). Given that, it made sense to have 'rm' run with the least 
> amount of privilege needed to do its job.

I am constantly bemused by the number of "setuid root" commands, when a 
simple "setgid whatever" will achieve the same task.

My mantra has always been: "If you think you need setuid root, then you 
are probably thinking wrong."

My favourite here is the "ps" command:

     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

(I didn't check my Penguin box, because I don't think that I'll like what 
I'll see.)

-- Dave

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