Linux: List All Users
Another very common request, both form my Unix/Linux beginner users and from the visitors to Unix Tutorial blog. Usually, user list is needed because you plan on doing something with it – so please leave a comment and let me know what it is. Who knows, there might be a quicker and easier way of doing the same!
List all users with getent
This is probably the quicked and easiest way of getting the list of users in your Linux system, along with most relevant info about each of them:
greys@ec2 ~]$ getent passwd root:x:0:0:root:/root:/bin/bash bin:x:1:1:bin:/bin:/sbin/nologin daemon:x:2:2:daemon:/sbin:/sbin/nologin adm:x:3:4:adm:/var/adm:/sbin/nologin lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin sync:x:5:0:sync:/sbin:/bin/sync shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt mail:x:8:12:mail:/var/spool/mail:/sbin/nologin operator:x:11:0:operator:/root:/sbin/nologin games:x:12:100:games:/usr/games:/sbin/nologin ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin nobody:x:99:99:Nobody:/:/sbin/nologin avahi-autoipd:x:170:170:Avahi IPv4LL Stack:/var/lib/avahi-autoipd:/sbin/nologin systemd-bus-proxy:x:999:997:systemd Bus Proxy:/:/sbin/nologin systemd-network:x:998:996:systemd Network Management:/:/sbin/nologin dbus:x:81:81:System message bus:/:/sbin/nologin polkitd:x:997:995:User for polkitd:/:/sbin/nologin rpc:x:32:32:Rpcbind Daemon:/var/lib/rpcbind:/sbin/nologin tss:x:59:59:Account used by the trousers package to sandbox the tcsd daemon:/dev/null:/sbin/nologin rpcuser:x:29:29:RPC Service User:/var/lib/nfs:/sbin/nologin nfsnobody:x:65534:65534:Anonymous NFS User:/var/lib/nfs:/sbin/nologin postfix:x:89:89::/var/spool/postfix:/sbin/nologin sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin chrony:x:996:993::/var/lib/chrony:/sbin/nologin centos:x:1000:1000:Cloud User:/home/centos:/bin/bash
IMPORTANT: if your Linux system is part of an AD or LDAP infrastructure, the getent passwd command will get you all the users in AD, rather than just those locally created on your Linux server.
List all users from /etc/passwd
You can also just look at the contents of the /etc/passwd file: it will look very similar to the getent output:
[greys@ec-ws1 ~]$ cat /etc/passwd root:x:0:0:root:/root:/bin/bash bin:x:1:1:bin:/bin:/sbin/nologin daemon:x:2:2:daemon:/sbin:/sbin/nologin adm:x:3:4:adm:/var/adm:/sbin/nologin lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin sync:x:5:0:sync:/sbin:/bin/sync shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt mail:x:8:12:mail:/var/spool/mail:/sbin/nologin operator:x:11:0:operator:/root:/sbin/nologin games:x:12:100:games:/usr/games:/sbin/nologin ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin nobody:x:99:99:Nobody:/:/sbin/nologin avahi-autoipd:x:170:170:Avahi IPv4LL Stack:/var/lib/avahi-autoipd:/sbin/nologin systemd-bus-proxy:x:999:997:systemd Bus Proxy:/:/sbin/nologin systemd-network:x:998:996:systemd Network Management:/:/sbin/nologin dbus:x:81:81:System message bus:/:/sbin/nologin polkitd:x:997:995:User for polkitd:/:/sbin/nologin rpc:x:32:32:Rpcbind Daemon:/var/lib/rpcbind:/sbin/nologin tss:x:59:59:Account used by the trousers package to sandbox the tcsd daemon:/dev/null:/sbin/nologin rpcuser:x:29:29:RPC Service User:/var/lib/nfs:/sbin/nologin nfsnobody:x:65534:65534:Anonymous NFS User:/var/lib/nfs:/sbin/nologin postfix:x:89:89::/var/spool/postfix:/sbin/nologin sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin chrony:x:996:993::/var/lib/chrony:/sbin/nologin centos:x:1000:1000:Cloud User:/home/centos:/bin/bash
Extract usernames from passwd with awk
All these lists are fine, but they’re not easily actionable in scripts or any other command line processing in Unix. The reason for this is, of course, because we’re getting too much information: instead of just the list of usernames, we’re looking at lots of passwd fileds like full name, user id, group if, user shell and so on.
So the next step is probably extracting usernames from the output we received. Here’s how we can do it: we’ll use the awk field separator to split fields.
Here’s the result:
[greys@ec-ws1 ~]$ cat /etc/passwd | awk -F: '{print $1}'
root
bin
daemon
adm
lp
sync
shutdown
halt
mail
operator
games
ftp
nobody
avahi-autoipd
systemd-bus-proxy
systemd-network
dbus
polkitd
rpc
tss
rpcuser
nfsnobody
postfix
sshd
chrony
centos
That’s it for today! Stay tuned for more!