https://www.2daygeek.com/6-easy-ways-to-check-user-name-and-other-information-in-linux
This is very basic topic, everyone knows how to find a user information in Linux using id command. Some of the users are filtering a user information from /etc/passwd file.
We also using these commands to get a user information.
You may ask, Why are you discussing this basic topic? Even i thought the same, there is no other ways except this two but we are having some good alternatives too.
Those are giving more detailed information compared with those two, which is very helpful for newbies.
This is one of the basic command which helps admin to find out a user information in Linux. Everything is file in Linux, even user information were stored in a file.
We can find a user information using the below six methods.
getent command shows user details similar to /etc/passwd file, it shows every user details as a single line with seven fields.
The lslogins utility is inspired by the logins utility, which first appeared in FreeBSD 4.10.
This is very basic topic, everyone knows how to find a user information in Linux using id command. Some of the users are filtering a user information from /etc/passwd file.
We also using these commands to get a user information.
You may ask, Why are you discussing this basic topic? Even i thought the same, there is no other ways except this two but we are having some good alternatives too.
Those are giving more detailed information compared with those two, which is very helpful for newbies.
This is one of the basic command which helps admin to find out a user information in Linux. Everything is file in Linux, even user information were stored in a file.
Suggested Read :
(#) How To Check User Created Date On Linux
(#) How To Check Which Groups A User Belongs To On Linux
(#) How To Force User To Change Password On Next Login In Linux
All the users are added in (#) How To Check User Created Date On Linux
(#) How To Check Which Groups A User Belongs To On Linux
(#) How To Force User To Change Password On Next Login In Linux
/etc/passwd file. This keep
user name and other related details. Users details will be stored in
/etc/passwd file when you created a user in Linux. The passwd file
contain each/every user details as a single line with seven fields. id :Print user and group information for the specified username.getent :Get entries from Name Service Switch libraries./etc/passwd file :The /etc/passwd file contain each/every user details as a single line with seven fields.finger :User information lookup programlslogins :lslogins display information about known users in the systemcompgen :compgen is bash built-in command and it will show all available commands for the user.
1) Using id Command
id stands for identity. print real and effective user and group IDs. To print user and group information for the specified user, or for the current user.# id daygeek uid=1000(daygeek) gid=1000(daygeek) groups=1000(daygeek),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),118(lpadmin),128(sambashare)Below are the detailed information for the above output.
uid (1000/daygeek):It displays user ID & Namegid (1000/daygeek):It displays user’s primary group ID & Namegroups:It displays user’s secondary groups ID & Name
2) Using getent Command
The getent command displays entries from databases supported by the Name Service Switch libraries, which are configured in /etc/nsswitch.conf.getent command shows user details similar to /etc/passwd file, it shows every user details as a single line with seven fields.
# 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 uucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologin operator:x:11:0:operator:/root:/sbin/nologin games:x:12:100:games:/usr/games:/sbin/nologin gopher:x:13:30:gopher:/var/gopher:/sbin/nologin ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin nobody:x:99:99:Nobody:/:/sbin/nologin dbus:x:81:81:System message bus:/:/sbin/nologin vcsa:x:69:69:virtual console memory owner:/dev:/sbin/nologin abrt:x:173:173::/etc/abrt:/sbin/nologin haldaemon:x:68:68:HAL daemon:/:/sbin/nologin ntp:x:38:38::/etc/ntp:/sbin/nologin saslauth:x:499:76:Saslauthd user:/var/empty/saslauth:/sbin/nologin postfix:x:89:89::/var/spool/postfix:/sbin/nologin sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin tcpdump:x:72:72::/:/sbin/nologin centos:x:500:500:Cloud User:/home/centos:/bin/bash prakash:x:501:501:2018/04/12:/home/prakash:/bin/bash apache:x:48:48:Apache:/var/www:/sbin/nologin nagios:x:498:498::/var/spool/nagios:/sbin/nologin rpc:x:32:32:Rpcbind Daemon:/var/lib/rpcbind:/sbin/nologin nrpe:x:497:497:NRPE user for the NRPE service:/var/run/nrpe:/sbin/nologin magesh:x:502:503:2g Admin - Magesh M:/home/magesh:/bin/bash thanu:x:503:504:2g Editor - Thanisha M:/home/thanu:/bin/bash sudha:x:504:505:2g Editor - Sudha M:/home/sudha:/bin/bashBelow are the detailed information about seven fields.
magesh:x:502:503:2g Admin - Magesh M:/home/magesh:/bin/bash
Username (magesh):Username of created user. Characters length should be between 1 to 32.Password (x):It indicates that encrypted password is stored at /etc/shadow file.User ID (UID-502):It indicates the user ID (UID) each user should be contain unique UID. UID (0-Zero) is reserved for root, UID (1-99) reserved for system users and UID (100-999) reserved for system accounts/groupsGroup ID (GID-503):It indicates the group ID (GID) each group should be contain unique GID is stored at /etc/group file.User ID Info (2g Admin - Magesh M):It indicates the command field. This field can be used to describe the user information.Home Directory (/home/magesh):It indicates the user home directory.shell (/bin/bash):It indicates the user’s bash shell.
# getent passwd | cut -d: -f1 root bin daemon adm lp sync shutdown halt mail uucp operator games gopher ftp nobody dbus vcsa abrt haldaemon ntp saslauth postfix sshd tcpdump centos prakash apache nagios rpc nrpe magesh thanu sudhaTo display only home directory users, use the below format.
# getent passwd | grep '/home' | cut -d: -f1 centos prakash magesh thanu sudha
3) Using /etc/passwd file
The/etc/passwd is a text file that contains each user
information, which is necessary to login Linux system. It maintain
useful information about users such as username, password, user ID,
group ID, user ID info, home directory and shell. The /etc/passwd file
contain every user details as a single line with seven fields as
described below.# 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 uucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologin operator:x:11:0:operator:/root:/sbin/nologin games:x:12:100:games:/usr/games:/sbin/nologin gopher:x:13:30:gopher:/var/gopher:/sbin/nologin ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin nobody:x:99:99:Nobody:/:/sbin/nologin dbus:x:81:81:System message bus:/:/sbin/nologin vcsa:x:69:69:virtual console memory owner:/dev:/sbin/nologin abrt:x:173:173::/etc/abrt:/sbin/nologin haldaemon:x:68:68:HAL daemon:/:/sbin/nologin ntp:x:38:38::/etc/ntp:/sbin/nologin saslauth:x:499:76:Saslauthd user:/var/empty/saslauth:/sbin/nologin postfix:x:89:89::/var/spool/postfix:/sbin/nologin sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin tcpdump:x:72:72::/:/sbin/nologin centos:x:500:500:Cloud User:/home/centos:/bin/bash prakash:x:501:501:2018/04/12:/home/prakash:/bin/bash apache:x:48:48:Apache:/var/www:/sbin/nologin nagios:x:498:498::/var/spool/nagios:/sbin/nologin rpc:x:32:32:Rpcbind Daemon:/var/lib/rpcbind:/sbin/nologin nrpe:x:497:497:NRPE user for the NRPE service:/var/run/nrpe:/sbin/nologin magesh:x:502:503:2g Admin - Magesh M:/home/magesh:/bin/bash thanu:x:503:504:2g Editor - Thanisha M:/home/thanu:/bin/bash sudha:x:504:505:2g Editor - Sudha M:/home/sudha:/bin/bashBelow are the detailed information about seven fields.
magesh:x:502:503:2g Admin - Magesh M:/home/magesh:/bin/bash
Username (magesh):Username of created user. Characters length should be between 1 to 32.Password (x):It indicates that encrypted password is stored at /etc/shadow file.User ID (UID-502):It indicates the user ID (UID) each user should be contain unique UID. UID (0-Zero) is reserved for root, UID (1-99) reserved for system users and UID (100-999) reserved for system accounts/groupsGroup ID (GID-503):It indicates the group ID (GID) each group should be contain unique GID is stored at /etc/group file.User ID Info (2g Admin - Magesh M):It indicates the command field. This field can be used to describe the user information.Home Directory (/home/magesh):It indicates the user home directory.shell (/bin/bash):It indicates the user’s bash shell.
# cut -d: -f1 /etc/passwd root bin daemon adm lp sync shutdown halt mail uucp operator games gopher ftp nobody dbus vcsa abrt haldaemon ntp saslauth postfix sshd tcpdump centos prakash apache nagios rpc nrpe magesh thanu sudhaTo display only home directory users, use the below format.
# cat /etc/passwd | grep '/home' | cut -d: -f1 centos prakash magesh thanu sudha
4) Using finger Command
The finger comamnd displays information about the system users. It displays the user’s real name, terminal name and write status (as a ‘‘*’’ after the terminal name if write permission is denied), idle time and login time.# finger magesh Login: magesh Name: 2g Admin - Magesh M Directory: /home/magesh Shell: /bin/bash Last login Tue Jul 17 22:46 (EDT) on pts/2 from 103.5.134.167 No mail. No Plan.Below are the detailed information for the above output.
Login:User’s login nameName:Additional/Other information about the userDirectory:User home directory informationShell:User’s shell informationLAST-LOGIN:Date of last login and other information
5) Using lslogins Command
It displays information about known users in the system. By default it will list information about all the users in the system.The lslogins utility is inspired by the logins utility, which first appeared in FreeBSD 4.10.
# lslogins -u UID USER PWD-LOCK PWD-DENY LAST-LOGIN GECOS 0 root 0 0 00:17:28 root 500 centos 0 1 Cloud User 501 prakash 0 0 Apr12/04:08 2018/04/12 502 magesh 0 0 Jul17/22:46 2g Admin - Magesh M 503 thanu 0 0 Jul18/00:40 2g Editor - Thanisha M 504 sudha 0 0 Jul18/01:18 2g Editor - Sudha MBelow are the detailed information for the above output.
UID:User idUSER:Name of the userPWD-LOCK:password defined, but lockedPWD-DENY:login by password disabledLAST-LOGIN:Date of last loginGECOS:Other information about the user
6) Using compgen Command
compgen is bash built-in command and it will show all available commands, aliases, and functions for you.# compgen -u root bin daemon adm lp sync shutdown halt mail uucp operator games gopher ftp nobody dbus vcsa abrt haldaemon ntp saslauth postfix sshd tcpdump centos prakash apache nagios rpc nrpe magesh thanu sudha
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