users

The "users" command line tool is a Unix/Linux command used to display the list of users currently logged into the system. It retrieves this information from the "/var/run/utmp" file, which keeps track of active user sessions. When executed without any options or arguments, the "users" command simply lists the usernames of all currently logged-in users in a single line. The usernames are separated by spaces and displayed in the order of their login sessions. The "users" command is often used in conjunction with other commands, such as "who" or "w", to obtain more detailed information about logged-in users and their activities. By default, the "users" command only displays the usernames, but it can be piped along with other commands to perform additional actions. The "-q" option can be used to display the total number of logged-in users instead of listing their usernames. Another useful option is "-a", which displays the usernames, the terminal line number, login time, idle time, and the host from which they are connected. The "users" command can also be used with the "-s" option to display the total number of logged-in users in a short format. Overall, the "users" command is a simple yet effective tool for quickly identifying and listing all the users currently logged into a Unix/Linux system.