The Command Line Interface (CLI) is the fundamental method of interacting with Linux/Unix/OS X systems. When Linux and Unix were first developed, the CLI was the only way of communicating with the system.
Today, with the many Graphical User Interfaces ( GUIs) available, fewer users are now being exposed to what can be done from the command line. In particular, users of OS X systems are commonly ignorant of what can be done through their terminal.
The intent of this page and the posts that it references are to introduce the new Linux user and the OS X user to what can be done through the CLI.
What are CLI Commands
Commands that are entered at the command line are simply programs that have been developed over the years and are now part of the Unix/Linux/OS X distribution that you are using. There are hundreds of commands, some you will use often, others you may never use.
|apropos||*||*||search command descriptions for keyword|
|bzip2||*||*||file compression/decompression with the Burrows-Wheeler block sorting text compression algorithm and Huffman coding|
|cat||*||*||concatenate and print file|
|chsh||*||*||change user shell|
|chgrp||*||*||change group ownership|
|dd||*||*||convert and copy files|
|file||*||*||determine file type|
|history||*||*||display the commands entered at the command line|
|look||*||*||List all lines of sorted text file that begin with specified word|
|ls||*||*||list directory contents|
|man||*||*||format and display the on-line manual pages|
|netstat||*||*||print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships|
|pwd||*||*||print working directory|
|sudo||*||*||execute a command as another user|
|tcpdump||*||*||capture and analyze network traffic|
|time||*||*||time a commands execution|
|top||*||*||watch process related details such as CPU and memory usage|
|whatis||*||*||Short description of command|
|zcat||*||*||View compressed file|