How to List All Users in Linux

The /etc/passwd file in Linux is a file that contains a list of users, and information about those users. We can use this file to list all users that exist in our system. For example, using the “cat” command will output the whole file. Notice that every line starts with the username field.

oot@bt:~# cat /etc/passwd
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/bin/sh
bin:x:2:2:bin:/bin:/bin/sh
sys:x:3:3:sys:/dev:/bin/sh
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/bin/sh
man:x:6:12:man:/var/cache/man:/bin/sh
lp:x:7:7:lp:/var/spool/lpd:/bin/sh
mail:x:8:8:mail:/var/mail:/bin/sh
news:x:9:9:news:/var/spool/news:/bin/sh
uucp:x:10:10:uucp:/var/spool/uucp:/bin/sh
proxy:x:13:13:proxy:/bin:/bin/sh
www-data:x:33:33:www-data:/var/www:/bin/sh
backup:x:34:34:backup:/var/backups:/bin/sh
list:x:38:38:Mailing List Manager:/var/list:/bin/sh
irc:x:39:39:ircd:/var/run/ircd:/bin/sh
gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/bin/sh
libuuid:x:100:101::/var/lib/libuuid:/bin/sh
syslog:x:101:103::/home/syslog:/bin/false
sshd:x:102:65534::/var/run/sshd:/usr/sbin/nologin
landscape:x:103:108::/var/lib/landscape:/bin/false
messagebus:x:104:112::/var/run/dbus:/bin/false
nobody:x:65534:65534:nobody:/nonexistent:/bin/sh
mysql:x:105:113::/var/lib/mysql:/bin/false
avahi:x:106:114::/var/run/avahi-daemon:/bin/false
snort:x:107:115:Snort IDS:/var/log/snort:/bin/false
statd:x:108:65534::/var/lib/nfs:/bin/false
usbmux:x:109:46::/home/usbmux:/bin/false
pulse:x:110:116::/var/run/pulse:/bin/false
rtkit:x:111:117::/proc:/bin/false
festival:x:112:29::/home/festival:/bin/false
postgres:x:1000:1000::/home/postgres:/bin/sh

Now, if we want to refine our search and filter out all that extra information and just print the usernames, we can use the “awk” command like this:

awk -F ':' '{print $1}' /etc/passwd

In this command the “-F” option tells awk the separating field, in this case the colon “:”, and the {print $1} option, is just to print out the first field, which is the username field.

root@bt:~# awk -F ':' '{print $1}' /etc/passwd
root
daemon
bin
sys
sync
games
man
lp
mail
news
uucp
proxy
www-data
backup
list
irc
gnats
libuuid
syslog
sshd
landscape
messagebus
nobody
mysql
avahi
snort
statd
usbmux
pulse
rtkit
festival
postgres
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