`uid` UID/GID example

This example demonstrates how to query user and group information using the POSIX getpwuid_r(), getpwnam_r(), getgrgid_r(), and getgrnam_r() functions.

Command Syntax:

uid -uid <uid>
uid -uname <name>
uid -gid <gid>
uid -gname <name>
uid -h

Synopsis. The uid command queries and displays user or group information from the system’s password and group databases.

Options

`-uid <uid>`	Show user information by numeric user ID.
`-uname <name>`	Show user information by user name.
`-gid <gid>`	Show group information by numeric group ID.
`-gname <name>`	Show group information by group name.
`-h`	Show help statement with all available options.

Query User by ID

To query user information by numeric UID:

nsh> uid -uid 0
Name:   root
UID:    0
GID:    0
Home:   /
Shell:  /bin/sh

The output displays:

Name: The login name
UID: The numeric user ID
GID: The primary group ID
Home: The home directory
Shell: The default shell

Query User by Name

To query user information by login name:

nsh> uid -uname root
Name:   root
UID:    0
GID:    0
Home:   /
Shell:  /bin/sh

Query Group by ID

To query group information by numeric GID:

nsh> uid -gid 0
Name:    root
Passwd:
GID:     0
Members:

The output displays:

Name: The group name
Passwd: The group password (usually empty)
GID: The numeric group ID
Members: Comma-separated list of group members

Query Group by Name

To query group information by group name:

nsh> uid -gname root
Name:    root
Passwd:
GID:     0
Members:

Help

To display usage information:

nsh> uid -h
USAGE:
      uid -uid <uid>    - Show user info by ID
      uid -uname <name> - Show user info by name
      uid -gid <gid>    - Show group info by ID
      uid -gname <name> - Show group info by name
      uid -h            - Show this help info

Configuration

The uid example can be enabled in the NuttX configuration:

CONFIG_EXAMPLES_UID=y

Optional configuration:

CONFIG_EXAMPLES_UID_PROGNAME – Program name. Default uid.
CONFIG_EXAMPLES_UID_PRIORITY – Task priority. Default 100.
CONFIG_EXAMPLES_UID_STACKSIZE – Stack size. Default DEFAULT_TASK_STACKSIZE.

uid UID/GID example