## login ![TRON: Legacy](tron.jpg) > In the movie _TRON: Legacy_, Linux is rebranded "SolarOS" in reference to [Solaris](), another Unix OS --- Start the VM to boot the previously installed Debian system. Do the following for both a user and the [superuser](https://en.wikipedia.org/wiki/Superuser) (`root`) : - Log in - Clear the console using the keyboard shortcut - Change the password to a space : `" "` - Show the command history using five keystrokes or less (using autocompletion) - Log out using the keyboard shortcut ### Just numbers Login as [`root`](https://en.wikipedia.org/wiki/Superuser) on the third [Linux console](https://en.wikipedia.org/wiki/Linux_console). Check the Internet connectivity with the command `ping google.com`. After a few hops, interrupt the program with : Ctrl + C. Behind every name in a computer system there is a number (ID, index, address, etc) : - User identifier - `root` → `0` - `student` → `1000` - IP address - google.com → 216.58.214.14 (quad-dotted notation) → `3627734542` - tencent.com → 117.169.101.44 (quad-dotted notation) → `1974035756` - File inode - `/etc/fstab` → `44696029` - `.profile` → `59639363` - Port - `HTTP` → `80` - `HTTPS` → `443` - Process identifier - `cron` → `254` Names exist because they are human readable, but behind the scenes they are converted into numbers, unique in their namespace : - A domain name can have several IP addresses, but an IP address can only identify one domain name - Several processes may have the same name, but a PID identifies a single process Find the commands to get : - the inode of a specific file - the current user ID - the PID of a program, for example `bash`