在Linux中,什么是/ etc / passwd文件?
/etc/passwd in Linux is a file that stores the list of users on the system along with important information regarding these users. Identifying users uniquely is essential and necessary at the time of
/etc/passwd in Linux is a file that stores the list of users on the system along with important information regarding these users. Identifying users uniquely is essential and necessary at the time of login. /etc/passwd is used by Linux system at the time of login. The file should be readable by all users but write permission should only belong to the root user.
Linux中的/ etc / passwd是一个文件,用于存储系统上的用户列表以及有关这些用户的重要信息。 登录时唯一地标识用户是必不可少的。 / etc / passwd在登录时由Linux系统使用。 该文件应为所有用户可读,但写许可权应仅属于root用户。
了解/ etc / passwd文件 (Understanding the /etc/passwd file)
To view the contents of the file use cat command.
要查看文件的内容,请使用cat命令。
$ cat /etc/passwd
The output will look something like this. Here each line represents a user. Each user has a list of parameters separated by ‘:’
输出将如下所示。 每行代表一个用户。 每个用户都有一个用“:”分隔的参数列表
The seven fields are :
七个字段是:
- Login name 登录名
- Encrypted Password 加密密码
- UID number UID号
- GID number GID号码
- GECOS GECOS
- Home directory 主目录
- Login shell 登录外壳
Let’s see what each of them mean :
让我们看看它们各自的含义:
- Login name: The unique name given to a user. It is case sensitive.
登录名 :给用户的唯一名称。 区分大小写。
- Encrypted Password: This field is for the encrypted password. However, in most modern Linux systems, the password is stored in a shadow file named /etc/shadow. The ‘x’ in the second field represents that the password is stored in a shadow file.
加密密码 :此字段用于加密密码。 但是,在大多数现代Linux系统中,密码存储在名为/ etc / shadow的影子文件中。 第二个字段中的“ x”表示密码存储在影子文件中。
- UID number: A unique ID assigned for each user. The system identifies a user by its UID number. The root user gets UID 0 which is reserved. UID 1-99 are reserved for predefined accounts. These are also called fake logins. In most Linux systems UID for new users starts from 1000.
UID号 :为每个用户分配的唯一ID。 系统通过其UID号标识用户。 根用户获得保留的UID 0。 UID 1-99保留用于预定义帐户。 这些也称为假登录。 在大多数Linux系统中,新用户的UID从1000开始。
- GID number: GID is used to identify the group user belongs to. Information about groups is stored in /etc/group file. In Linux, a user can belong in up to 16 groups.
GID号 :GID用于标识组用户所属。 有关组的信息存储在/ etc / group文件中。 在Linux中,一个用户最多可以属于16个组。
- GECOS: stands for General Electric Comprehensive Operating Supervisor. This field allows the admin to store additional information about the user. This field can have multiple entries in a comma-delimited list. Information such as full name, phone number, the designation can be stored in this field.
GECOS :代表通用电气综合运营主管。 该字段允许管理员存储有关用户的其他信息。 该字段在逗号分隔列表中可以有多个条目。 姓名,电话号码,名称等信息可以存储在此字段中。
- Home directory: This field contains the absolute path to the user’s home directory. When a user logs in, the system puts him/her directly in his/her home directory.
主目录:此字段包含用户主目录的绝对路径。 用户登录后,系统会将其直接放置在其主目录中。
- Login shell: This field is for specifying the program that will run automatically whenever the user logs in. It’s typically a command interpreter (shell). 登录外壳程序 :此字段用于指定用户登录时将自动运行的程序。它通常是命令解释器(外壳程序)。
创建一个用户 (Create a user )
We can use the useradd command to create a new user. Make sure to run the command with root access.
我们可以使用useradd命令创建一个新用户。 确保以root用户访问权限运行命令。
$ useradd Adam
This creates a user by the name Adam.
这将创建一个名为Adam的用户。
修改GECOS字段 (Modify GECOS field)
To modify the GECOS field for Adam, use usermod command.
要修改Adam的GECOS字段,请使用usermod命令。
$ usermod -c "DevOp expert" Adam
显示特定用户的条目 (Display entry for a particular user)
From the etc/passwd file to get the entry for a single user use grep command.
使用grep命令从etc / passwd文件获取单个用户的条目。
$ grep Adam /etc/passwd
As we can see that GECOS field has been successfully updated for user Adam.
如我们所见,GECOS字段已成功为用户Adam更新。
We break the values into their respective fields :
我们将值分为各自的字段:
- Login name: Adam 登录名: Adam
- Encrypted Password: x (shadow file) 加密密码: x (影子文件)
- UID number: 1001 UID号: 1001
- GID number: 1002 GID号: 1002
- GECOS: DevOp expert GECOS: DevOp专家
- Home directory: /home/Adam 主目录: / home / Adam
- Login shell: /bin/sh 登录shell: / bin / sh
结尾词 (Ending words)
As a Linux administrator, it is important to know the /etc/passwd file at the back of your hand. Understand what each field means and keep a track of users on the system. To learn more about /etc/passwd file refer to this Wikipedia page for passwd command.
作为Linux管理员,了解手背的/ etc / passwd文件非常重要。 了解每个字段的含义,并跟踪系统上的用户。 要了解有关/ etc / passwd文件的更多信息,请参阅Wikipedia页面上的passwd命令。
翻译自: https://www.journaldev.com/41380/etc-passwd-file-in-linux
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