Find unowned files via command line?

Question

I'm interested in making a list of files not owned by any package and sending it to a text file I can review. I found this thread, which suggests pacpal (link appears to be broken now) and this script. I could try the script, but I noted from a bit back that the Arch news page listed a one-liner for finding unowned packages in the preparation of moving /usr/lib -> /lib:
$ find /bin /sbin /usr/sbin -exec pacman -Qo -- {} + >/dev/null
Here's the script linked to above, for reference:
#!/bin/bash
# Utility to generate a list of all files that are not part of a package
# Author: Spider.007 / Sjon
TMPDIR=`mktemp -d`
FILTER=$(sed '1,/^## FILTER/d' $0 | tr '\n' '|')
FILTER=${FILTER%|}
cd $TMPDIR
find /bin /boot /etc /lib /opt /sbin /usr /var | sort -u > full
pacman -Ql | tee owned_full | cut -d' ' -f2- | sed 's/\/$//' | sort -u > owned
grep -Ev "^($FILTER)" owned > owned- && mv owned- owned
echo -e '\033[1mOwned, but not found:\033[0m'
comm -13 full owned | while read entry
do
echo [`grep --max-count=1 $entry owned_full|cut -d' ' -f1`] $entry
done | sort
grep -Ev "^($FILTER)" full > full- && mv full- full
echo -e '\n\033[1mFound, but not owned:\033[0m'
comm -23 full owned
rm $TMPDIR/{full,owned,owned_full} && rmdir $TMPDIR
exit $?
## FILTERED FILES / PATHS ##
/boot/grub
/dev
/etc/X11/xdm/authdir
/home
/media
/mnt
/proc
/root
/srv
/sys
/tmp
/var/abs
/var/cache
/var/games
/var/log
/var/lib/pacman
/var/lib/mysql
/var/run
/var/tmp
Is there any reason to use a script like the above compared to such a simple script, which appears to just be spitting a list of all files in /bin, /urs/sbin, and /sbin into `pacman -Qo`. What I can't figure out is what the end of the command does (the `-- {} + > /dev/null`). From various attempts to pipe that output into a text file, I've noticed that it just gets filled with the owned files... so I'm guessing something in there is filtering so that unowned get printed to stdout and owned go to /dev/null. I can't figure out how to redirect the unowned to a text file.
Thanks for any suggestions.

Answer 1

alphaniner wrote:"--" is often used to tell the program there are no more options. I didn't see it in the manpage, but that's the case with pacman as well.* The "{} +" is part of the find -exec argument, search for {} in the find manpage.
Ah. Thanks for that. I'd been googling things like " linux command line '-- {}'" and not getting any hits. I combined the arguments incorrectly! Thanks for letting me know that this was part of `find`, as I was also looking in the man page for pacman wrongly.
alphaniner wrote:
The >/dev/null is redirecting stdout (list of owned files) to oblivion. The list of unowned files (and other errors) goes to stderr. To redirect stderr you use "2>" so try
find /bin /sbin /usr/sbin -exec pacman -Qo -- {} + >/dev/null 2>unowned_files
Perfect, and now I understand how `pacman -Qo` is working: it sends the answer to stdout if it knows the answer and to stderr if it doesn't find a hit. Thanks!