In Linux or Unix-like operating system, the ‘/etc/passwd’ file stores all user information. This file contains the normal (regular) and system users.
In this tutorial, I will show you how to list users in Linux using the command line.
The commands that I have listed below would work on all Linux distros like Ubuntu/Centos and Arch Linux.
1) From “/etc/passwd – Using Cut & Awk Command
As mentioned above the file /etc/passwd stores all users list regardless of created account for a human, service associated account or system functional user. Each line of /etc/passwd is a distinct user. These commands should work on Centos/Ubuntu/Arch and other Linux distros as well.
Use below command to list all user
$ cat /etc/passwdroot: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 nobody:x:99:99:Nobody:/:/sbin/nologin dbus:x:81:81:System message bus:/:/sbin/nologin polkitd:x:999:998:User for polkitd:/:/sbin/nologin hacluster:x:189:189:cluster user:/home/hacluster:/sbin/nologin avahi-autoipd:x:170:170:Avahi IPv4LL Stack:/var/lib/avahi-autoipd:/sbin/nologin rpc:x:32:32:Rpcbind Daemon:/var/lib/rpcbind:/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 ...you get the list without un-necessary information by using,
$ cut -d : -f 1 /etc/passwdHere cut command is used to extract 1st field from the file named ‘/etc/passwd’ using the delimiter (;) and display required output on the console
Remember, cut command needs option otherwise it gives error.
root daemon bin sys sync games man lp mail news uucp proxy www-data backup ....Let’s try something more,
$ cat /etc/passwd | grep "/home" |cut -d: -f1syslog administrator linoxide ...Now what we have done is, we have piped the previous command output to another variable “cut”
$ cut -d: -f1-d defines delimiter “:”
-f1 display first field of line i.e. username.
Let us try some more formatting using Awk utility. This tool enables a system administrator to build commands that define text patterns that need to be searched in a file.
The following awk command will list all users with full name and home directory along with the login,
$ awk -F":" '{print "Login:" $1 "tName:" $5 "tHome:" $6}' /etc/passwdlook at the output, you will see a well-formatted and decorated output.
Login:root Name:root Home:/root Login:daemon Name:daemon Home:/usr/sbin Login:bin Name:bin Home:/bin Login:sys Name:sys Home:/dev Login:sync Name:sync Home:/bin Login:games Name:games Home:/usr/games Login:man Name:man Home:/var/cache/man Login:lp Name:lp Home:/var/spool/lpd Login:mail Name:mail Home:/var/mail Login:gnats Name:Gnats Bug-Reporting System (admin) Home:/var/lib/gnats ...The following command will list all users including system and regular (normal) users:
$ awk -F: '{print $1}' /etc/passwdSample Output $ awk -F: '{print $1}' /etc/passwd root daemon bin sys sync games man lp mail www-data backup list irc gnats testuserTo list all regular user (only)
Linux systems keep ‘system’ accounts below a specific user id, so use awk search for UIDs higher than certian limit.
$ awk -F: '$3 >= 500 {print}' /etc/passwd2) Getent command
The getent command do the same like cut command we have seen before, getent command fetches entries from databases supported by the Name Service library. If one or more options are provided to command, then only the entries that match the option will be displayed. Otherwise, all entries will be displayed. the syntax for getting end command,
getent [option] [database]Display all Users
This is same as that of listing users using cat /etc/passwd, if no other options are provided the getent command uses passwd as database reference and lists all users.
$ getent passedroot: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 saslauth:x:996:76:"Saslauthd user":/run/saslauthd:/sbin/nologin libstoragemgmt:x:995:994:daemon account for libstoragemgmt:/var/run/lsm:/sbin/nologin avahi:x:70:70:Avahi mDNS/DNS-SD Stack:/var/run/avahi-daemon:/sbin/nologin ntp:x:38:38::/etc/ntp:/sbin/nologin mysql:x:27:27:MariaDB Server:/var/lib/mysql:/sbin/nologin radvd:x:75:75:radvd user:/:/sbin/nologin vivek:x:1000:1000:vivek:/home/vivek:/bin/bash vboxadd:x:991:1::/var/run/vboxadd:/bin/false linoxide:x:9999:9999:official:/home/lino_dir:/bin/bash ...Find all Groups
The below commands list all group without any condition or matches if no other options are provided the getent command uses group as database reference and lists all groups.
$ getent grouproot:x:0: bin:x:1: daemon:x:2: sys:x:3: adm:x:4: tty:x:5: disk:x:6: mail:x:12:postfix man:x:15: dialout:x:18: floppy:x:19: haclient:x:189: unbound:x:997: colord:x:996: dip:x:40: usbmuxd:x:113: ...Search All groups with specific user
$ getent group | grep usernameThe above command fetches all group, passing username to pipe lists only matching row. The output has a group and username belonging to that group.
The below command is for advanced formatting using awk, cut & sed command together to list all users and users belongs to specific group.
cat /etc/group | awk -F: '{print $1, $3, $4}' | while read group gid members; do members=$members,$(awk -F: "$4 == $gid {print "," $1}" /etc/passwd); echo "$group: $members" | sed 's/,,*/ /g';done
