The Linux core toolset provides us with some commands to view user-related information.

Print User Identity

We can use the id command to view the user’s ID, name, user’s group ID and name, etc:

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id

Print the User ID

If we add the -u option, the command will only output the user’s ID:

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id -u    # This is equivalent to id --user

Print the Group ID

If we add the -g option, the command will only output the group ID:

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id -g    # This is equivalent to id --group

Print the Group ID and the Supplementary Groups

If we add the -G option, the command will only output the supplementary groups’ ID:

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id -G    # This is equivalent to id --groups

Print the Name, Group Name, Supplementary Group Name of the User

If we add the -un, -gn or -Gn option, the command will only output the user’s name, group name, and supplementary group’s name:

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id -un    # This is equivalent to id -u --name
id -gn    # This is equivalent to id -g --name
id -Gn    # This is equivalent to id -G --name

Print the Real ID, Real Group ID, Real Supplementary Group ID of the User

If we add the -ur, -gr or -Gr option, the command will only output the user’s real ID, group real ID, and supplementary group’s real ID:

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id -ur    # This is equivalent to id -u --real
id -gr    # This is equivalent to id -g --real
id -Gr    # This is equivalent to id -G --real

Print the Security Context of the User

If we add the -Z option, the command will only output the user’s security context:

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id -Z    # This is equivalent to id --context

Print Current Login Name

We can use logname command to display the user name of the current login:

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logname

Print Who is Currently Logged in

We can use who command to display the logged in user names and other login details:

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who

Print Effective User ID

We can use whoami command to display the effective user ID:

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whoami    # This is equivalent to id -un

Print Group Names the User Belongs to

We can use group command to display the user’s belonging group names:

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groups    # This is equivalent to id -Gn

Or we can specify a user name to view the group to which the user belongs:

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groups [username]

Print Users Names

We can use users command to display the logged in users’ names:

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users

Print User Details With finger

We can use finger command to display the user names currently logged in:

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yum install finger -y
finger root

References 20 User information

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