Linux Commands: Tips to View User UID and GID

Linux operating system is a widely used open source operating system. It provides users with a wealth of command line tools, allowing users to manage the system more easily. In a Linux system, each user has a unique user identifier (User ID, UID) and a group identifier (Group ID, GID). Understanding the user's UID and GID is very important for system management and file permission management. This article will introduce several techniques for viewing the user's UID and GID to better manage the Linux system.

1. Use the id command

The id command can display the UID and GID of the current user, as well as the additional groups to which it belongs. Just enter the following command in the terminal:

id

Sample output:

uid=1000(john) gid=1000(john) groups=1000(john ),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),113(lpadmin),128(sambashare)

In the above output, uid represents the user The UID, gid represents the GID of the main group to which the user belongs, and groups represents the additional groups to which the user belongs. In this example, user john's UID is 1000 and his GID is also 1000.

2. Use the getent command

The getent command is used to obtain user and group related information, including the user's UID and GID. You can obtain the corresponding information by specifying the user name or group name. Here is an example:

getent passwd john

Example output:

john:x:1000:1000:John Doe:/home/john:/bin/bash

In the above output, the third field is the UID of the user, and the fourth field is the GID of the primary group to which the user belongs. In this example, user john's UID is 1000 and his GID is also 1000.

3. Use the grep command

In Linux systems, user and group information is usually stored in the /etc/passwd and /etc/group files. You can use the grep command to find the UID and GID of a specific user or group. Here is an example:

grep john /etc/passwd

Sample output:

john:x:1000:1000:John Doe:/home/john:/bin /bash

In the above output, the third field is the user's UID, and the fourth field is the GID of the primary group the user belongs to. In this example, user john's UID is 1000 and his GID is also 1000.

To sum up, through the methods introduced above, we can easily view the user's UID and GID, which is very helpful for system management and permission management. Mastering these skills can enable us to manage Linux systems more efficiently.

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