April 19, 2016 Useradd/du/df/passwd/usermod command

First, Useradd command

Useradd Command-m-u-s-g Common
-C: Add note text, note text is saved in passwd's remarks column.
-D: Specifies the start directory at which the user logged in.
-D: Change the preset value. (Modify default configuration file)
-e: Specifies the expiration date of the account and the default is permanent.
-F: Specify the number of days after the password expires to close the account.
-G: Specifies the starting group to which the user belongs.
-G: Specifies the additional group to which the user belongs.
-M: Automatically establish the user's login directory.
-M: Do not automatically create a user's login directory.
-N: Cancels the creation of a group named after the user name.
-R: Set up the system account.
-S: Specifies the shell to use when the user is logged in.
-U: Specifies the user ID number.





-e expire_date account termination date. The specified format for the date is mm/dd/yy.
-F Inactive_days Account expires a few days after the permanent stop right. The account number at 0 o'clock is immediately deactivated. This function is turned off when the value is-1, and the default is-1
-G Initial_group group name or number as the user Login start Group (group). The group name must be a name that exists already. Group numbers are also required for existing groups. The preset group number is 1.
-G group,[...] defines this user as a member of this heap of groups. Each group uses the "," area, and cannot be mixed with blank characters. The group name is limited to the-G option. Defines the starting group for which the value is a consumer.
-M user directory is automatically created if it does not exist. If you use the-K option, the files within the Skeleton_dir will be copied to the user directory. However, files in the/etc/skel directory will also be duplicated in the past. Any directories in the Skeleton_diror/etc/skel are also created in the user directory. The-k with-M does not establish directories and does not copy any files as presets.
-M does not establish a user directory, even if the/etc/login.defs system file is set up to create a user directory.

-U uid The user's ID value. Must be a unique ID value unless the-o option is used. The number cannot be negative. The preset is not less than 999 and increases successively. 0~999 is traditionally reserved for use in system accounts. Changing the preset worth-D option appears, Useradd shows the default value now, or updates the preset with the command column

-e default_expire_date user account stop date.
-F default_inactive account expires several days after the stop right.
-G Default_group New account start group name or ID. The group name must be a name that exists already. The group ID must also be an existing group.
/etc/skel file. bash_loght. bash_profile. BASHRC user's initial directory for storing files
/etc/default/useradd the default setting when adding users. Initializes the settings file with the specified parameter precedence
Groupadd Add Group command-G
Related Paths/etc/shadow shadow-
passwd--stdin
-N two times minimum number of days for password modification
-X two times the maximum number of days for password modification
How long after the-I password expires prohibit login use
-W Prompt user How many days prompt to change password
Min Max Inactive Warning
Summary of User management commands:
1, and user-related configuration file knowledge points:
/etc/passwd account files and different column contents
/etc/shadow account password file and different column contents
/etc/group groups of files and different column contents
/etc/gshadow group password file and different column contents
2. User Management commands
Useradd-u-g-g-s-m-e-c-D
Correspondence/etc/skel,/etc/default/useradd,/etc/login.defs
Userdel-r
Usermod-u-g-g-s-m-e-c-d-l-u-l
Id
Chage-l-e-m-w-m-I.
passwd--stdin-n-i-w-X (suid-bit focus)
Su
Sudo
Visudo

Second, Usermod command

Usermod can modify user groups to increase user outreach projects

-G Expansion group u specify ID G start ID

Usermod-u 500-g 512-g 522 user1

2.USERMOD-L Carlton Lock

Usermod-u Unlocking

Iii. passwd Order

passwd + Username If it is the root user, do not add

Yum-y Install expect installation package

After the installation is done

MKPASSWD automatically generate passwords

Iv. DF Command

Df-t Viewing the file system type

DF does not look like a swap partition, you need to use free to see

Df-h can know how much the partition uses

Df-k in k units

Df-i viewing the usage of inode

V. du command

Du is mainly looking at the size of the file

Du-m in units of M

Du-h can be randomly displayed according to the size of the file

Du-sh/file path/size of the specified file

The main difference between Ls-ih and Du-sh is that the former is looking at the file itself and the latter from disk

April 19, 2016 Useradd/du/df/passwd/usermod command