User commands and logs
whoami
For convenience, many distributions and users make the current user part of the command prompt – some for every user, others only for the command prompt. However, on systems without such prompts, remembering which account you are logged into can become confusing, such as when you are using su
to change accounts while administering or configuring. For such systems, the whoami
command (Figure 6) can serve as a general compass. It is used without options – unless you are interested in the version number – and returns only the login name of the current account.
who
The who
command is one of the most important commands for gathering information about users and general system settings (Figure 7).
Unmodified by any options, the who
command lists the users except root who are currently logged in and the date and time they logged in. Users may be listed multiple times if they have one or more virtual terminals open. However, if you add the -q
or --count
option, the same information is displayed in a short format that emphasizes the current number of logins. Different options also give basic system information (see Table 1).
Table 1
System Information from the who Command
Short Option | Long Option | Information |
---|---|---|
|
|
Lists dead processes |
|
|
Displays the last time the system was booted |
|
|
Prints active processes |
|
|
Shows current runlevel |
|
|
Gives the last time the system clock was changed |
id
When you log in to Linux, you establish your real username and groups. However, you also can use commands like sudo
and su
to run as a different or effective user. With the id
command, you can quickly find both real and effective usernames.
The unmodified id
command (Figure 8) gives the real UID for the current account, plus the GIDs for any groups to which the account belongs. However, if you add the -a
option, you get the effective UID. Similarly, the -g
or --group
command displays the real GID, but -G
or --groups
(note the spelling difference) prints all the group IDs. If you do not have multiple logins, you might not notice any difference between the real and effective user.
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
Gnome 47.1 Released with a Few Fixes
The latest release of the Gnome desktop is all about fixing a few nagging issues and not about bringing new features into the mix.
-
System76 Unveils an Ampere-Powered Thelio Desktop
If you're looking for a new desktop system for developing autonomous driving and software-defined vehicle solutions. System76 has you covered.
-
VirtualBox 7.1.4 Includes Initial Support for Linux kernel 6.12
The latest version of VirtualBox has arrived and it not only adds initial support for kernel 6.12 but another feature that will make using the virtual machine tool much easier.
-
New Slimbook EVO with Raw AMD Ryzen Power
If you're looking for serious power in a 14" ultrabook that is powered by Linux, Slimbook has just the thing for you.
-
The Gnome Foundation Struggling to Stay Afloat
The foundation behind the Gnome desktop environment is having to go through some serious belt-tightening due to continued financial problems.
-
Thousands of Linux Servers Infected with Stealth Malware Since 2021
Perfctl is capable of remaining undetected, which makes it dangerous and hard to mitigate.
-
Halcyon Creates Anti-Ransomware Protection for Linux
As more Linux systems are targeted by ransomware, Halcyon is stepping up its protection.
-
Valve and Arch Linux Announce Collaboration
Valve and Arch have come together for two projects that will have a serious impact on the Linux distribution.
-
Hacker Successfully Runs Linux on a CPU from the Early ‘70s
From the office of "Look what I can do," Dmitry Grinberg was able to get Linux running on a processor that was created in 1971.
-
OSI and LPI Form Strategic Alliance
With a goal of strengthening Linux and open source communities, this new alliance aims to nurture the growth of more highly skilled professionals.