Linux commands: About sudo

sudo Introduction to Commands:

Make a user execute a command as another user

1 . The configuration file is:/etc/sudoers

configuration file format:

Format: Who which_hosts= (runas) command

Who: Indicates which user which_hosts: which host

runas: What user is executing command: What commands to execute

For multiple users, logging on to multiple servers, executing multiple identities, multiple commands, and defining aliases:

Who:user_alias User Aliases

Which_hosts:host_alias Host Aliases

Runas:runas_alias with what user alias

Command:cmnd_alias command Aliases

Aliases must all and only use a combination of uppercase English letters:

User alias Definition Format:

User_alias useradmin = System User name,% group name, and other user aliases that you have defined

User aliases: Can include: System user name, group name (format:% group name), other defined user aliases in the middle, separated by

Host alias definition Format:

Host_alias hostadmin = host name, IP address, network address segment, other defined host aliases

Runas_alias alias Format:

Runas_alias runasname = user name,% group name, other defined runas aliases

Cmnd_alias Command alias Format:

Cmnd_alias COMMANDNAME = command path, directory (all commands in this directory), other pre-defined command aliases

Usage: Enables Hadoop users to execute useradd usermod commands for all hosts

Vim/etc/sudoers Edit the sudo configuration document and add the following on the last line:

Hadoop all= (Root)/usr/sbin/useradd,/usr/sbin/usermod

2 . Command function:

enables one user to execute a command on a host as another user

3 . Command parameters:

-L: Lists all sudo class commands that the current user can use

-K: Disable authentication information (default sudo remembers password for 5 minutes)

Add Tag: nopasswd:passwd:

4 . Command instance:

1. Enable Hadoop users to execute useradd usermod commands for all hosts

Vim/etc/sudoers Edit the sudo configuration document and add the following on the last line:

Hadoop all= (Root) nopasswd:/usr/sbin/useradd,/usr/sbin/usermod

NOPASSWD: No password is required for all commands that are behind the label

Hadoop all= (Root) nopasswd:/usr/sbin/useradd, PASSWD:/usr/sbin/usermod

PASSWD: Indicates the need for a password,

2. Enable the Sudoers profile using alias mode

Vim/etc/sudoers

User_alias useradmin = hadoop,%hadoop,%useradmin #表示hadoop用户, Hadoop Group, useradmin Group

Cmnd_alias useradmincmnd =/usr/sbin/useradd,/usr/sbin/usermod,/user/bin/passwd [A-Za-z]*,! /USR/BIN/PASSWD root #命令别名, which means that useradd usermod/user/bin/passwd can be executed via sudo [a-za-z]* means that the Execute passwd command must be followed by at least one letter! /USR/BIN/PASSWD root indicates that you cannot execute the passwd root command (!) to modify the root user password

useradmin all= (Root) nopasswd:useradmincmnd

[Email protected] root]$ SUDO/USR/SBIN/PASSWD root

Password:

John is isn't in the sudoers file. This incident would be reported.

[Email protected] ~]$ SUDO/USR/BIN/PASSWD

Sorry, user John is not allowed to execute '/usr/bin/passwd ' as the root on Localhost.localdomain.

[Email protected] ~]$ sudo/usr/bin/passwd Donggen

Changing password for user Donggen.

New UNIX Password:

Bad Password:it is the too short

Retype new UNIX Password:

Passwd:all authentication tokens updated successfully.

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Linux commands: About sudo