|Unix Command||What it does|
|pwd||- indicates the current working directory|
|cd /usr/local/chemistry||- changes from current directory to "/usr/local/chemistry"|
|cd||- changes to home directory|
|ls||- lists files in current directory|
|ls -lt||- lists files with time and size|
|ls -lt | head||- lists the most recently created files|
The Unix shell acts as an interface between the user and the Unix operating system. It consists of high-level (human understandable) commands that tell the Unix operating system what to do. This information in turn is transferred to the hardware (CPU) in terms of low-level (machine understandable) commands. The user brings up a "window", called a Unix shell into which high-level commands are typed.