Editing Rm (Unix) (section)

=== Preventing accidental deletion ===
Commands like <code>rm -rf *</code> are relatively risky since they can delete many files in an unrecoverable way. Such commands are sometimes referenced in anecdotes about disastrous mistakes,<ref name="Linux/UNIX: Delete a file">{{cite web|last=Gite|first=Vivek|title=Linux/UNIX: Delete a file|url=http://www.cyberciti.biz/faq/howto-linux-unix-delete-remove-file/|publisher=Nixcraft|access-date=24 November 2011}}</ref> such as during the production of the film ''[[Toy Story 2]]''.<ref name="Panzarino">{{cite web |last1=Panzarino |first1=Matthew |title=How Toy Story 2 Got Deleted Twice, Once on Accident, Again on purpose |url=https://thenextweb.com/news/how-pixars-toy-story-2-was-deleted-twice-once-by-technology-and-again-for-its-own-good |website=TNW {{!}} Media |access-date=27 September 2022 |language=en |date=21 May 2012}}</ref> 

To minimize the risk of accidental file deletions, a common technique is to hide the default {{code|rm}} command behind an alias or a function that includes the interactive option. For example:

<syntaxhighlight lang="bash">
alias rm="rm -i"
</syntaxhighlight>

or

<syntaxhighlight lang="bash">
rm () { /bin/rm -i "$@" ; }
</syntaxhighlight>

Then, by default, {{code|rm}} requires the user to confirm removing each file by pressing {{key|Y}} or {{key|N}} plus {{key|Return}}. To bypass confirmation, a user can include the <code>-f</code> option (as the option specified later on the expanded command line "<code>rm -i -f</code>" takes precedence). 

Unfortunately this can lead to other accidental removals since it trains users to be careless about the wildcards they hand to <code>rm</code>, as well as encouraging a tendency to mindlessly press {{key|Y}} and {{key|Return}} to confirm.{{Citation needed|date=July 2012}} Users have even been seen going as far as using <code>yes | rm ''files''</code>, which automatically confirms the deletion of each file. {{Citation needed|date=July 2012}}

A compromise that allows users to confirm just once, encourages proper wildcarding, and makes verification of the list  easier can be achieved with something like:

<syntaxhighlight lang="bash">
if [ -n "$PS1" ] ; then
  rm () 
  { 
      ls -FCsd "$@"
      echo 'remove[ny]? ' | tr -d '\012' ; read
      if [ "_$REPLY" = "_y" ]; then
          /bin/rm -rf "$@"
      else
          echo '(cancelled)'
      fi
  }
fi
</syntaxhighlight>

Arguably, this function should not be made into a [[shell script]], which would run a risk of it being found ahead of the system <code>rm</code> in the search path, nor should it be allowed in non-interactive shells where it could break batch jobs. Enclosing the definition in the <code>if [ -n "$PS1" ] ; then ....  ; fi</code> construct protects against the latter.

Other commands are designed to prevent accidental deletion; including {{code|safe-rm}}<ref>{{Cite web|url=https://launchpad.net/safe-rm/+index|title=Safe-rm in Launchpad|website=Launchpad}}</ref> and {{code|trash}}.<ref>{{Cite web|url=https://github.com/andreafrancia/trash-cli|title=andreafrancia/trash-cli|date=September 12, 2020|via=GitHub}}</ref>