/etc/passwd

Understanding /etc/passwd format

The /etc/passwd file contains one entry per line for each user (user account) of the system. All fields are separated by a colon : symbol. Total of seven fields as follows. Generally, /etc/passwd file entry looks as follows:

test:x:0:0:root:/root:/bin/bash

[as divided by colon (:)]

1. Username: It is used when user logs in. It should be between 1 and 32 characters in length.

2. Password: An x character indicates that encrypted password is stored in /etc/shadow file. Please note that you need to use the passwd command to compute the hash of a password typed at the CLI or to store/update the hash of the password in /etc/shadow file, in this case, the password hash is stored as an "x".

3. User ID (UID): Each user must be assigned a user ID (UID). UID 0 (zero) is reserved for root and UIDs 1-99 are reserved for other predefined accounts. Further UID 100-999 are reserved by system for administrative and system accounts/groups.

4. Group ID (GID): The primary group ID (stored in /etc/group file)

5. User ID Info: The comment field. It allow you to add extra information about the users such as user’s full name, phone number etc. This field use by finger command.

6. Home directory: The absolute path to the directory the user will be in when they log in. If this directory does not exists then users directory becomes /

7. Command/shell: The absolute path of a command or shell (/bin/bash). Typically, this is a shell. Please note that it does not have to be a shell.

Example of /etc/passwd file

root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/usr/sbin/nologin
man:x:6:12:man:/var/cache/man:/usr/sbin/nologin
lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin
mail:x:8:8:mail:/var/mail:/usr/sbin/nologin
news:x:9:9:news:/var/spool/news:/usr/sbin/nologin
uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin
proxy:x:13:13:proxy:/bin:/usr/sbin/nologin
www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin
backup:x:34:34:backup:/var/backups:/usr/sbin/nologin
list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin
irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin
gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin
systemd-timesync:x:100:102:systemd Time Synchronization,,,:/run/systemd:/bin/false
systemd-network:x:101:103:systemd Network Management,,,:/run/systemd/netif:/bin/false
systemd-resolve:x:102:104:systemd Resolver,,,:/run/systemd/resolve:/bin/false
syslog:x:104:108::/home/syslog:/bin/false
_apt:x:105:65534::/nonexistent:/bin/false
messagebus:x:106:110::/var/run/dbus:/bin/false
uuidd:x:107:111::/run/uuidd:/bin/false
lightdm:x:108:117:Light Display Manager:/var/lib/lightdm:/bin/false
ntp:x:109:119::/home/ntp:/bin/false
avahi:x:110:120:Avahi mDNS daemon,,,:/var/run/avahi-daemon:/bin/false
colord:x:111:123:colord colour management daemon,,,:/var/lib/colord:/bin/false
dnsmasq:x:112:65534:dnsmasq,,,:/var/lib/misc:/bin/false
hplip:x:113:7:HPLIP system user,,,:/var/run/hplip:/bin/false
nm-openconnect:x:114:124:NetworkManager OpenConnect plugin,,,:/var/lib/NetworkManager:/bin/false
nm-openvpn:x:115:125:NetworkManager OpenVPN,,,:/var/lib/openvpn/chroot:/bin/false
pulse:x:116:126:PulseAudio daemon,,,:/var/run/pulse:/bin/false
rtkit:x:117:128:RealtimeKit,,,:/proc:/bin/false
saned:x:118:129::/var/lib/saned:/bin/false
usbmux:x:119:46:usbmux daemon,,,:/var/lib/usbmux:/bin/false
geoclue:x:103:105::/var/lib/geoclue:/usr/sbin/nologin
nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin
vboxadd:x:999:1::/var/run/vboxadd:/bin/false
user1:x:1000:1000:user1,,,:/home/user1:/bin/bash
user2:x:1001:1001:user2,,,:/home/user2:/bin/bash
user3:x:1002:1002:user3,,,:/home/user3:/bin/bash
user4:x:1003:1003:user4,,,:/home/user4:/bin/bash
statd:x:120:65534::/var/lib/nfs:/usr/sbin/nologin
user5:x:1004:1004:user5,,,:/home/user5:/bin/bash
user6:x:1005:1005:user6,,,:/home/user6:/bin/bash
mysql:x:121:131:MySQL Server,,,:/var/mysql:/bin/bash
user7:x:1006:0:user7,,,:/home/user7:/bin/bash
user8:x:1007:1007:user8,,,:/home/user8:/bin/bash
sshd:x:122:65534::/run/sshd:/usr/sbin/nologin
new:$1$new$p7ptkEKU1HnaHpRtzNizS1:0:0:root:/root:/bin/bash