safe rm, how?

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Newsgroups:  comp.unix.shell
Date:        Sat, 19 Nov 2005 18:50:48 +0000

 > I wish there is a '-n' switch for rm (to default answer no) so as
 > not to remove write-protected file. How can I do that? Why "yes no | rm *"
 > won't work?
 >
 > touch a b c d
 > touch aa bb cc dd
 > chmod a-w ??
 >
 > $ rm *
 > rm: remove write-protected regular empty file `aa'? ^C
 >
 > $ yes no | rm *
 >
 > $ ls | wc -l
 > 0
 >
 > The yes command provide "no" to rm, but why it still deleted all my files?
[...]

Because rm detects that it is not speaking to a human (because its standard input is not a terminal), so doesn't ask any question.

With zsh,

rm *(.Uw)

will only remove regular (.) files owned by yourself (U) and writable by yourself (w).

Stephane CHAZELAS

safe rm, how?

use find, like:

find -perm 644 -print0 | xargs -0r rm

You can have more options on setting up the permission bits with "find", for example:

find -perm +w -type f -print0 | xargs -0r rm

this delete all files having "write" at 'u','g', or 'o' bit

find -perm +w -type f -prune -o -print0 | xargs -0r rm

this selects all files skipped by the first command and then delete:

XC - xicheng