I need to find all users home directories listed using grep from /etc/passwd

Question

I have a question similar to another one on this site where the individual had to find a list of all users using grep or awk from /etc/passwd. That worked for me but I've tried translating it to find and list the home directories of them also. I already know you can't do it in one line so I know I would use a pipeline. I've done my research online but I can't figure it out the problem is. If I use grep and do something like the following:

   grep -oE '^[/*/]$' /etc/passwd 

...i t would probably give me an error or it will also show me the /bin/bash files which is not what I want. I just need the user names and their home directories listed using grep! I'm also not sure if the * will show other forward-slashes as characters, as some home directories have more than just two /'s (forward-slashes).

Answer 1

Grep is really not the tool for parsing out data this way, grep is more for pattern matching and you're trying to do text-processing. You would want to use awk.

awk -F":" '$7 == "/bin/false" {print "User: "$1 "Home Dir: "$6}' /etc/passwd

awk The command

-F":" Sets the data delimiter to :

$7 == "/bin/false" Checks if the 7th data column is /bin/false

{print "User: "$1 "Home Dir: "$6}' Says to print the first column and sixth column in the specified format.

/etc/passwd Is the file we're processing

Answer 2

You can use cut to split files with columns on a specific delimiter:

cut -d: -f6 /etc/passwd

Or -f1,6 for columns (fields) 1 and 6.

Answer 3

As others have pointed out, grep isn't the best tool for this. If you insist on using it, and if your grep supports the -o (only print the matched portion of the line) and -P (use Perl Compatible Regular Expressions), you can do this:

$ grep -oP '^[^:]+|.*:\K[^:]+(?=:[^:]+)' /etc/password
terdon
/home/terdon
bob
/home/bob

^{Note that this will print all users, including system users. I am only showing 4 lines as an example.}

That will print the user name and home directories of all users but on separate lines. You then need to join each pair of lines to get them together:

$ grep -oP '^[^:]+|.*:\K[^:]+(?=:[^:]+)' /etc/passwd | perl -pe 's/\n/ : / if $.%2'
root : /root
bin : /bin
daemon : /
mail : /var/spool/mail
ftp : /srv/ftp
http : /srv/http
uuidd : /
dbus : /
nobody : /
systemd-journal-gateway : /
systemd-timesync : /
systemd-network : /
systemd-bus-proxy : /
systemd-resolve : /
systemd-journal-upload : /
systemd-coredump : /
systemd-journal-remote : /
terdon : /home/terdon
avahi : /
polkitd : /
colord : /var/lib/colord
rtkit : /proc
gdm : /var/lib/gdm
git : /
bob : /home/bob

Explanation

The regex has two parts, it looks for ^[^:]+ OR (that's what the | means) .*:\K[^:]+(?=:[^:]+). The first looks for one or more non-: characters from the beginning of the line. This matches the user name. The second part looks for as many characters as possible until a : (.*:) and then discards them (that's what the \K does) so they're not printed. It then matches a string of non-: which is followed by : and non-:. The (?=foo) construct is called a positive lookahead and is a way of matching the characters after a pattern without including those characters in the match itself.

The perl command will replace newlines with : and spaces if the current line number ($.) is divisible by 2. So, every second line.

Answer 4

I believe that you can do this with "cut", using just one binary, avoiding pipes, reaching the same results as the other answers, but in a more elegant way :), like this:

$ cut -d : -f 1,6 /etc/passwd

root:/root
daemon:/usr/sbin
bin:/bin
sys:/dev
sync:/bin
games:/usr/games
man:/var/cache/man
lp:/var/spool/lpd
mail:/var/mail
news:/var/spool/news
....

If you wanna have an output better formatted + alphabetical order, here is, but the trade off is that, you have to use more binaries:

$ cut -d : -f 1,6 /etc/passwd | sort | column

avahi-autoipd:/var/lib/avahi-autoipd        man:/var/cache/man
avahi:/var/run/avahi-daemon                 messagebus:/var/run/dbus
backup:/var/backups                         news:/var/spool/news
bin:/bin                                    nobody:/nonexistent
clickpkg:/nonexistent                       ntp:/home/ntp
colord:/var/lib/colord                      proxy:/bin
daemon:/usr/sbin                            pulse:/var/run/pulse
dnsmasq:/var/lib/misc                       root:/root
games:/usr/games                            rtkit:/proc
gnats:/var/lib/gnats                        saned:/home/saned
hplip:/var/run/hplip                        speech-dispatcher:/var/run/speech-dispatcher
irc:/var/run/ircd                           sync:/bin
ivanleon:/home/ivanleon                     sys:/dev
kernoops:/                                  syslog:/home/syslog
libuuid:/var/lib/libuuid                    usbmux:/home/usbmux
lightdm:/var/lib/lightdm                    usermetrics:/var/lib/usermetrics
list:/var/list                              uucp:/var/spool/uucp
lp:/var/spool/lpd                           whoopsie:/nonexistent
lxc-dnsmasq:/var/lib/lxc                    www-data:/var/www
mail:/var/mail