====== Linux Cheatsheet ======

===== Files and Navigation =====

^ Command                  ^ Description                                                                              ^
| ''ls''                     | list all files/folders on current dir                                                    |
| ''ls -l''                  | formatted listing                                                                        |
| ''ls -la''                 | formatted listing including hidden files                                                 |
| ''cd <dir>''               | change directory to dir                                                                  |
| ''cd ..''                  | change to parent directory                                                               |
| ''cd ./<dir>''             | change to dir in parent directory                                                        |
| ''cd''                     | change to home directory                                                                 |
| ''pwd''                    | show current directory                                                                   |
| ''mkdir <dir>''            | create a directory dir                                                                   |
| ''rm <file>''              | remove file                                                                              |
| ''rm -f  <dir>''           | force remove file                                                                        |
| ''rm -r <dir>''            | remove directory dir                                                                     |
| ''rm -rf <dir>''           | force remove directory dir                                                               |
| ''rm -rf /''               | It's like exploding a nuclear bomb targeting your entire operating system. NEVER USE IT! |
| ''cp <file1> <file2>''     | copy file1 to file2                                                                      |
| ''mv <file1> <file2>''     | mv file1 to file2                                                                        |
| ''mv <file1> <dir/file2>'' | mv file1 to dir as file2                                                                 |
| ''touch <file>''           | create or update file                                                                    |
| ''cat <file>''             | output contents of file                                                                  |
| ''cat > <file>''           | write standard input into file                                                           |
| ''cat >> <file>''          | append standard input into file                                                          |
| ''tail -f <file>''         | output contents of file as it grows                                                      |

===== Processes =====

^ Command        ^ Description                        ^
| ''ps''           | display currently active processes |
| ''ps aux''       | detailed outputs                   |
| ''kill pid''     | kill process with process id (pid) |
| ''killall proc'' | kill all processes named proc      |

===== System Info =====

^ Command             ^ Description                  ^
| ''date''              | show current date/time       |
| ''uptime''            | show uptime                  |
| ''whoami''            | show you are logged in as    |
| ''w''                 | display who is online        |
| ''cat /proc/cpuinfo'' | display cpu info             |
| ''cat /proc/meminfo'' | display memory info          |
| ''free''              | show memory and swap usage   |
| ''du''                | show directory space usage   |
| ''du -sh''            | display readable sizes in GB |
| ''df''                | show disk usage              |
| ''uname -a''          | show kernel config           |

===== Networking =====

^ Command                 ^ Description                        ^
| ''ping host''             | ping host                          |
| ''whois domain''          | get whois for domain               |
| ''dig domain''            | get DNS for domain                 |
| ''dig -x host''           | reserve lookup host                |
| ''wget <file>''           | download file                      |
| ''wget -c <file>''        | continue stopped download          |
| ''wget -r <url>''         | recursively download file from url |
| ''curl <url>''            | output the webpage from url        |
| ''curl -o page.html url'' | writes the page to page.html       |
| ''ssh -p port user@host'' | connect using port                 |
| ''ssh -D user@host''      | connect and use bind port          |

===== Permissions =====

^ Command ^ Description               ^
| ''chmod'' | change permission of file |

  * 4 -> read ''r'' 
  * 2 -> write ''w''
  * 1 -> execute ''x''

**order**: owner/group/world -> ''-rwxrwxrwx''

Example:

* ''chmod 777'' rwx for everyone
* ''chmod 755'' rwx for owner, rx for group and world