### 1.2.1 Xcas interface

How you start Xcas in a graphical environment depends on which operating system you are using.

- If you are using Unix or Linux, you can usually find an entry for the program in a menu provided your desktop environment. Otherwise, you can start it from a terminal by typing

  xcas &

  If for some reason Xcas becomes unresponsive, you can open a terminal and type

  killall xcas

  This will kill any running Xcas processes. Xcas keeps an automatic backup files, so when you restart Xcas, you will be asked if you want to resume where you left off.
- If you are running Windows, use the explorer to go to the directory where Xcas is installed. In that directory is a file called xcas.bat. You can click on that file to start Xcas.
- If you are running Mac OS, use the Finder to go to the xcas_image.dmg file and double-click it. Then double-click the Xcas disk icon. Finally, you can double-click the Xcas program to launch Xcas.

When you start Xcas, a window will open with menu entries across the top, below that will be a bar giving information about the current Xcas configuration, and below that will be an entry line use to enter commands. This interface will be described in more detail later, but the menu item Help ▸ Interface will bring up an introduction.