Linux/etc/passwd,/etc/shadow,/etc/group files

1./etc/passwd

[Email protected] ~]# Cat/etc/passwdroot:x:0:0:root:/root:/bin/bashbin:x:1:1:bin:/bin:/sbin/nologindaemon:x:2:2: Daemon:/sbin:/sbin/nologinadm:x:3:4:adm:/var/adm:/sbin/nologinlp:x:4:7:lp:/var/spool/lpd:/sbin/nologinsync:x : 5:0:sync:/sbin:/bin/syncshutdown:x:6:0:shutdown:/sbin:/sbin/shutdown .....

Each field is separated by: and the fields contain the following information:

① login user name;

② user password;

③ UID of user account (in digital form)

④ user account Group ID (GID) (in digital form)

⑤ text Description of user account (called Memo field)

⑥ the location of the user home directory

⑦ User's default shell

Usermod is a user account modification tool

-L Modify the login name of the user account

-L Lock account so users cannot log in

-P Modify Account password

-U unlocks so that the user can log on.

CHPASSWD read the login password pair from the file and update the password

Chage change the expiration date of a password

CHFN Modify user account comment information

Chsh Modifying the default login shell for a user account

2./etc/shadow

[Email protected] ~]# cat/etc/shadowroot:$6$lrtcgaos$v/ f8z.wko94leoxrxjv4qeqmm8y2yd9z6bba0u3vtefljbutfhjbwfqwkxxkqti2gpyxcdm04tubze4w5nmdo.:17206:0:99999:7:::bin:* : 15980:0:99999:7:::d aemon:*:15980:0:99999:7:::adm:*:15980:0:99999:7:::lp:*:15980:0:99999:7:::sync:* : 15980:0:99999:7:::shutdown:*:15980:0:99999:7:::halt:*:15980:0:99999:7::: .....

As with/etc/passwd, each field of the/etc/shadow is also separated by: each field information is as follows

① the login name corresponding to the login field in the/etc/passwd file

② Password after encryption

③ the number of days since the password was last modified (calculated from January 1, 1970)

④ How many days before you change your password

⑤ How many days must you change your password

How many days before the ⑥ password expires remind the user to change their password

How many days after the ⑦ password expires disable the user account

⑧ the date the user account was disabled (expressed as the number of days from January 1, 1970 to the day)

⑨ reserved fields for future use

3./etc/group

[Email protected] ~]# Cat/etc/grouproot:x:0:bin:x:1:bin,daemondaemon:x:2:bin,daemonsys:x:3:bin,admadm:x:4:adm, Daemontty:x:5:disk:x:6:lp:x:7:daemonmem:x:8: .....

The/etc/group file has 4 fields:

① Group Name

② Group Password

③gid

④ List of users belonging to this group

USERMOD-G Group name username #在组中添加用户, the-G option adds the new group to the group list for the user account

Groupmod-n New group name old group name #更改组名

Linux/etc/passwd,/etc/shadow,/etc/group files