Linux allows you to enter multiple commands at one time. The only requirement is that you separate the commands with a semicolon.
Want to see how long you have been online and open your Web browser at the same time? Just combine the date command with Mozilla's command.
date; mozilla; date
Remember that commands are case sensitive, so the command to start Mozilla must be in lowercase to start the browser.
[sam@halloween sam]$date; mozilla; date Mon Feb 7 13:26:27 EST 2000 Mon Feb 7 14:28:32 EST 2000 [sam@halloween sam]$
Running the combination of commands prints out the time and date, starts Mozilla, and then prints the time and date again after you close Mozilla. The discrepancy between the two results from the date command shows that you were using Mozilla for just over an hour.