======Basic Commands and Filesystem Overview======
An overview of the Linux Filesystem and seven frequently-used Linux commands and examples of how to use them. For additional information about any of these commands, log onto an EECS machine and type <code>man command</code>
Replace "command" with the actual command for which you want the manual page, for example ''man ls''.

=====Linux Filesystem=====
The filesystem structure of Linux is much different from Windows. It is good to know a few of these differences before you start.

====General Overview====
In Windows, drives are mounted completely separately with drive letters. In Linux, drives are mounted in the filesystem. ''/'' is the root direcory of your boot drive filesystem. All mounted drives and filesystems in Linux exist somewhere under ''/''. All of the default directories in ''/'' (known as **standard subdirectories**) have a meaning and intended use to keep the filesystem organized. Some examples are as follows:

^ Directory  ^ Purpose  ^
| [[https://www.tldp.org/LDP/Linux-Filesystem-Hierarchy/html/the-root-directory.html|/]]  | The root of the filesystem.  |
| [[https://www.tldp.org/LDP/Linux-Filesystem-Hierarchy/html/bin.html|/bin]]  | Stores essential programs such as shells, ''ls'', etc.  |
| [[https://www.tldp.org/LDP/Linux-Filesystem-Hierarchy/html/etc.html|/etc]]  | Stores configurations for Linux, daemons, etc  |
| [[https://www.tldp.org/LDP/Linux-Filesystem-Hierarchy/html/var.html|/var]]  | Stores variable data like log files, etc.  |
| [[https://www.tldp.org/LDP/Linux-Filesystem-Hierarchy/html/home.html|/home]]  | Stores user home areas, like ''C:\\Users'' in Windows.  |
| [[https://www.tldp.org/LDP/Linux-Filesystem-Hierarchy/html/dev.html|/dev]]  | Stores device files.  |

====File Paths====
In a Linux shell, there are two types of paths. There are absolute paths (beginning in ''/'') that define a full path from the root directory and relative paths (paths that don't begin with ''/'') that are relative to your current directory. Example:

<code>
/home/netid > cp some_file Documents
# this copies some_file from your current directory into the Documents directory in your current directory

/home/netid > mv classes/cosc102/my_file.log /tmp
# this moves the file my_file.log (absolute path /home/netid/classes/cosc102/my_file.log) to the absolute path /tmp)
</code>

=====Commands=====
====ls====
The ''ls'' command lists directory contents.

^ Command  ^ Effects  ^
| ''ls''  | Lists the contents of the current working directory.  |
| ''ls dir-name''  | Lists the contents of the ''dir-name'' directory.  |
| ''ls -a''  | Lists the contents of the current working directory, including files that begin with a dot. (Dotfiles are not listed unless the -a option is used.)  |
| ''ls -l''  | Lists the contents of the current working directory in long format (including file owner, permissions, etc.).  |
====cd====
The ''cd'' command changes the current (working) directory.

^ Command  ^ Effects  ^
| ''cd''  | Changes to your home directory.  |
| ''cd foo''  | Changes to the ''foo'' directory.  |
| ''cd ..''  | Changes to the parent directory (i.e., move up one directory).  |

====cp====
The ''cp'' command copies files and directories.

^ Command  ^ Effects  ^
| ''cp src-file dest-file''  | Creates/overwrites ''src-file'' into ''dest-file''.  |
| ''cp src-file dest-dir''  | Copies/overwrites ''src-file'' into ''dest-dir/src-file''.  |
| ''cp -R src-dir dest-dir''  | Copies all files and subdirectories within the ''src-dir'' directory into the ''dest-dir'' directory. (The ''-R'' stands for “recursive”.)  |
| ''cp -i src dest''  | Copies the file/directory src to the file/directory dest, but prompts if any files or directories would be overwritten. (The ''-i'' stands for “interactive”.)  |

====mv====
The ''mv'' command moves or renames files and directories.

^ Command  ^ Effect  ^
| ''mv old-file new-file''  | Renames the file ''old-file'' to ''new-file''.  |
| ''mv src-file dest-dir''  | Moves the file ''src-file'' into ''dest-dir/src-file''.  |
| ''mv old-dir new-dir''  | Renames the ''old-dir'' directory to ''new-dir''.
| ''mv old-dir existing-dir''  | Moves the ''old-dir'' directory into the  ''existing-dir'' directory.  |
| ''mv -i src dest''  | Moves or renames ''src'' to ''dest'', but prompts if any files or directories would be overwritten. (The ''-i'' stands for “interactive”.)  |
====rm====
The ''rm'' command removes (i.e., deletes) files. (To remove directories, use ''rmdir'' if the directory is empty.)

^ Command  ^ Effects  ^
| ''rm foo''  | Deletes the file ''foo''.  |
| ''rm -r dir''  | Deletes the ''foo'' directory, including all of its files and subdirectories. (The ''-r'' stands for “recursive”.)  |
| ''rm -i file''  | Deletes the file ''foo'', but prompts before actually deleting it. (The ''-i'' stands for “interactive”.)  |

====mkdir====
The ''mkdir'' command makes a new directory.

^ Command  ^ Effects  ^
| ''mkdir foo''  | Creates a new directory named ''foo''.  |

====du====
The ''du'' command displays the amount of disk usage for specific files and directories.

^ Command  ^ Effects  ^
| ''du -s foo''  | Summarizes the disk usage of a file/directory ''foo'' in KB.  |
| ''du -sh .''  | Summarizes the disk usage of the current directory (represented by ''.'' in human-readable format (prints sizes using appropriate sizes such as KB, MB, GB) (''-h'' stands for human-readable.)  |

There is more information about using ''du'' to get under your disk quota in [[knowledge-base:linux-topics:quota]].