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Re: -e does not take effects in subshell

From: Linda Walsh
Subject: Re: -e does not take effects in subshell
Date: Tue, 18 Aug 2015 15:31:03 -0700
User-agent: Thunderbird

Greg Wooledge wrote:
On Tue, Aug 18, 2015 at 01:49:53PM -0700, Linda Walsh wrote:
Ex: rmx -fr (alias to rm --one-file-system -fr, since rm lacks the
-x switch like 'find, cp, mv, et al.) no longer works to clean
out a directory && stay on *one* file system.

When did POSIX or any historical Unix rm have a --one-file-system option?
You say "no longer works" as if it had EVER worked in the past.
Historically, linux had it going back to early 2000's (linux being a *nix platform) -- but historically, it wasn't
so easy to have features like 'bind/rbind', snapshots, multiple
virtual machines that need their own root (or chroot), etc.  If
you go back far enough symlinks weren't even around.

        I'm only talking about POSIX ~2001 or before.  After that
it started changing.  So it depends on how historical you are talking.
POSIX cmd language started with POSIX.2 in 1992, before that it
was purely a programming API.  It started including the cmd's as
a way of providing portable shell scripts.  Not as a way of
restricting users.

        While POSIX changed the 'rm' algorithm to no longer do
depth-first removal (now it's 2-pass, depth-first permissions check,
then depth-first removal).  But that's not the behavior of the historical

        Various "one-file-system" cp -x, find -x, du -x were added after
it became common to allow more complicated mount structures.

        I remember an early version of cygwin-coreutils-rm on Win7 that
didn't recognize symlinks or mountpoints (linkd/junctions) wandering
up out of the "C:\recycle bin" over to a documents folder on another

        Daily-backups do come in handy.
And yes, the standard way to do this (the only way with traditional
tools) would use find ... -xdev ... -exec rm {} +
        Which won't reliably work if your starting path is "pathname/."

but would with an rm -frx (or rmx -fr path/.").

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