关于linux:Linux基础用户相关

getent

getent is a common way to look up in user details on Linux;
getent is a Linux command that helps the user to get the entries in a number of important text files called databases;

Supported databases:

1. passwd shadow
2. group gshadow
2. ahosts ahostsv4 ahostsv6
2. aliases ethers 
4. hosts initgroups
2. netgroup networks  protocols rpc services 

Usage:
getent [OPTION...] database [key ...]

用户相干文件

/etc/passwd—

 格局：login_name：passwd(x)：UID：GID：GECOS：home_directory：shell

/etc/shadow—

 格局：login_name:passwd(sha512):
从 1970.01.01 起到明码最近一次被批改的工夫：明码再过几天能够被变更 (0- 任意)：明码再过几天必须被变更：明码过期前几天零碎揭示用户（默认 7 天）：明码过期几天后账号被锁定：从 1970.01.01 算起，多少天后账号生效 

/etc/group
/etc/gshadow

用户相干命令

useradd

useradd [OPTIONS] LOGIN
useradd -D -- 默认配置 /etc/default/useradd

newusers — update and create new users in batch

newusers [options] format_files
pw_name:pw_passwd:pw_uid:pw_gid:pw_gecos:pw_dir:pw_shell

su 和 sudo 的区别

su — Change the effective user id and group id to that of USER. A mere – implies -l. If USER not given, assume root.

su [options] [-] [USER [arg]...]

sudo — execute a command as another user

sudo [options] [<command>]
sudo -i -- run login shell as the target user
sudo -s -- run shell as the target user;

Different:

1. -The main difference between the two is that su requires the password of the target account, while sudo requires the password of the current user.
2. -Additionally，it is advisable to stick to sudo when performing tasks that require root privileges. By doing so, the current user is only granted privileged for the specified command.