Linux usermod command, user password management, mkpasswd command

Usermod Command

usermod Command is a command to change a user's properties, Usermod Similar to the usage of useradd, there are several uses of this command:

u sermod  -u number username   change the user's uid user1 user's uid 1111

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u Sermod -G user group or GID username change user's gid: For example, I change the user group of the user1 user to grp:

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u Sermod - D path username Changes the user's home directory, for example:

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u Sermod - s shell username changes the user's shell, for example:

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  u Span style= "font-family: ' The song body '; font-weight:bold;font-size:20px;" >sermod user group or gid username   extended user Group ( expansion group ) gid Span style= "font-family: ' The song Body '; > There is only one, for example I will user1 user add one more Span style= "FONT-FAMILY:CALIBRI;" >grp2

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u Sermod -G user group or gid, user group or GID username This usage can extend multiple user groups:

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The ID user1 command can view the uid,gid , and user groups of the user1 User:

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User Password Management

The passwd command is a command used to modify a user's password, and many people should have used this command several times.

to change the root user's password:

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Password Section Two * indicates that the user's password is locked, is not available, meaning that this user is not able to log on

To change the password for a normal user:

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password Section two ! indicates that the user does not have a password, which means that the user is not able to log on

Passwd-l command can lock a user's password, for example, I want to lock the user1 user, after the successful lock will be in front of this user's password plus two ! Number:

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The passwd-u command can unlock the user's password and cancel the two before the user's password ! the number disappears:

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The Usermod-l command can also lock the user's password, but unlike using the passwd-l command to lock the password, this command locks the password in front of only one ! Number:

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The Usermod-u command is the lock that unlocks the password:

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The passwd--stdin command can change the user's password, which may be used on shell scripts:

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Using this command to change the user password is clear text, and you do not need to enter a second confirmation password.

So you can set a string to the user's password directly with a pipe character:

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The ECHO-E command can appear as a line break in a single line of command

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so you can take advantage of this even if the passwd command does not add the --stdin option, you can set the password directly with a single command:

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The principle of setting a password:

password length is greater than or equal to 10 bits ( except for special cases )

Password to include numeric capital letters lowercase letters and special characters

The password better not be regular

Passwords do not include personal information, such as name, birthday, etc.

Password change regularly

MKPASSWD Command

mkpasswd is the abbreviation for Make password , which is a tool that is used to generate a password. Typically this command needs to be installed on its own and requires the installation of the expect package:

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after installation, you can use mkpasswd Command randomly generate a password:

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m kpasswd - L can specify the length of the generated password, for example I specify a password that generates a length of two

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You can also specify that the generated password includes several special symbols, for example, I want to generate a password with a password length of 3 with a special symbol:

command:mkpasswd-l 12-s 3

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Or specify that the generated password does not contain special characters:

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Linux usermod command, user password management, mkpasswd command