7

They say rm command defaults to the option --preserve-root. Is that right?

Otherwise I should put the line

alias rm='rm --preserve-root'`

in ~/.bashrc to make that option happen without typing it every time I run the rm command. To confirm this I ran type rm, and got rm is hashed (/bin/rm).

I expected rm is aliased to rm --preserve-root. Does anyone know what's going on with the rm command?

12
  • 1
    sorry I have no idea who "they" are, but I think you'll find it depends on your kernel & shell/bash version. I know some of the systems I use (which are still supported) don't have --preserve-root on rm.
    – guiverc
    Dec 1 '17 at 12:34
  • 1
    At least for me I get for sudo rm -r / the following message: rm: it is dangerous to operate recursively on '/' and rm: use --flag-i-wont-mention to override this failsafe
    – Videonauth
    Dec 1 '17 at 12:44
  • 1
    This is also present in the manpage for rm.
    – user595510
    Dec 1 '17 at 12:57
  • 1
    @guiverc It has nothing to do with the kernel, or your shell (bash or otherwise). It's a default option in GNU rm since some years, which is a separate program from your shell. (It's in coreutils in Debian and Ubuntu).
    – marcelm
    Dec 1 '17 at 13:46
  • 2
    For those who are wondering, the '--preserve-root' was made the default for rm in core-utils on 2016-09-02 in: git.savannah.gnu.org/gitweb/…
    – qneill
    Mar 28 '18 at 19:01
10

rm is not being aliased to rm --preserve-root, but the option is selected by default in the rm binary.

From the manpage of rm in Ubuntu 17.10, you can find the following details of the --preserve-root and --no-preserve-root options:

   --no-preserve-root
          do not treat '/' specially

   --preserve-root
          do not remove '/' (default)
2
  • I have read man page, but I totally missed the "(default)". Thanks for the reply. BTW when you mention 'rm binary', did you mean rm is programmed in that way??
    – Smile
    Dec 1 '17 at 12:56
  • @Smile Yes, that's what it means.
    – user595510
    Dec 1 '17 at 12:57

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