How to remove every file and folder recursively except for a few specific folders?

Question

Having the Busybox ash shell at hand, I wish to cleanup the /opt folder.

Cleanup means to remove every file and folder recursively except for a few exclusion paths that need to be left untouched.

Regression rm

# cd /opt && echo rm -rf \
   ./!(opt/etc/nginx|/opt/home|/opt/etc/config|/opt/usr/sbin|/opt/var/mlocate)
-sh: syntax error: unexpected "("

Regression find

This seems to do the job:

 # cd /opt && find ./ ! -path "./etc" ! -path "./etc/config" ! \
     -path "./etc/config/*" ! -path "./etc/nginx" ! -path "./etc/nginx/*" ! \
     -path "./home" ! -path "./home/*" ! -path "./usr" ! -path "./usr/sbin" ! \
     -path "./usr/sbin/*" ! -path "./var" ! -path "./var/mlocate" ! \
     -path "./var/mlocate/*" -exec rm -f {} \;; cd -

Any suggestion how to improve? Use -delete instead of -exec rm -f {} \? Handle rm: can't remove '.' or '..'? How to delete the empty directories without recursion rm -rf, in other words how to f.e. integrate rmdir?

---

Note: it's Busybox 1.24.2 and there is no shopt neither tac available. Defined functions:

[, [[, addgroup, adduser, ar, arping, ash, awk, base64, basename, blkid, blockdev, brctl, bunzip2, bzcat,
cat, chgrp, chmod, chown, chroot, clear, cmp, cp, crond, crontab, cryptpw, cut, date, dd, delgroup, deluser,
devmem, df, diff, dirname, dmesg, dos2unix, du, echo, egrep, env, expr, false, fgrep, find, free, fsync,
getty, grep, gunzip, gzip, halt, head, hexdump, hostid, hostname, id, ifconfig, insmod, iostat, ip, ipaddr,
ipcalc, iplink, ipneigh, iproute, iprule, iptunnel, kill, killall, klogd, less, ln, lock, logger, login,
losetup, ls, lsmod, lsusb, md5sum, mkdir, mkfifo, mknod, mkswap, mktemp, more, mount, mv, nc, netmsg,
netstat, nice, nslookup, ntpd, od, passwd, patch, pgrep, pidof, ping, ping6, pivot_root, poweroff, printf,
ps, pwd, readlink, reboot, renice, reset, rev, rm, rmdir, rmmod, route, run-parts, sed, seq, setconsole,
setserial, sh, sha1sum, sha256sum, sha512sum, sleep, sort, start-stop-daemon, stat, strings, stty, su,
swapoff, swapon, switch_root, sync, sysctl, syslogd, tail, tar, tee, telnet, telnetd, test, time, top, touch,
tr, traceroute, true, tty, udhcpc, umount, uname, uniq, unix2dos, unlink, unlzma, unxz, unzip, uptime,
usleep, vconfig, vi, wc, wget, which, xargs, xz, xzcat, yes, zcat

Answer 1

1.

According to jlliagre's answer at find - exec rm vs -delete \; can better be replaced with + to optimize the exec clause by not running the rm command for each and every match present on the file system.

2.

It needs an additional ! -path "./" to not generate rm: can't remove '.' or '..'.

Answer 2

Try:

cd /opt &&
  find . \( \
    -path ./etc/config -o \
    -path ./etc/nginx -o \
    -path ./home -o \
    -path ./usr/sbin -o \
    -path ./var/mlocate \) -prune -o \( \
      -type d -print0 -o -exec rm -f {} + \) |
    tr '\0\n' '\n\0' |
    tac |
    tr '\0\n' '\n\0' |
    xargs -r0 rmdir

-prune makes sure we don't even enter those skipped directories.

We delete non-directory files in the other directories. And leave the directories to process for after (tac won't output anything until find finishes because it starts with the last line).

We need to pass the list of directories in reverse order to rmdir as we need it do delete the content before the directory itself. Note that rmdir won't delete non-empty directories.

One usually uses -depth to process leaves before the branches that hold them, but we can't use -depth with -prune. For the same reason, we can't use -delete as it implies -depth.