17Jun/11
UNIX Command Line: Basics
Meant as a quick reference of basic commands for people who are new to using UNIX shell.
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Directories | Navigation | Listing | Permissions | Moving | Editing
Directory Examples:
File and directory paths in UNIX use the forward slash "/" to separate directory names.
| / | "root" directory |
| /usr | directory usr (sub-directory of / "root" directory) |
| /usr/SUBDIR | SUBDIR is a subdirectory of /usr |
Navigating the File System:
| pwd | Display the "present working directory", or current directory. |
| cd | Change current directory to your HOME directory. |
| cd /usr/SUBDIR | Change current directory to your HOME directory. |
| cd INIT | Change current directory to INIT which is a sub-directory of the current directory. |
| cd .. | Change current directory to the parent directory of the current directory. |
| cd $THISVARIES | Change current directory to the one defined by the environment variable 'THISVARIES'. |
| cd ~trin | Change the current directory to the user trin's home directory (if you have permission). |
Listing Directory Contents:
| ls | List a directory. |
| ls -l | List a directory in long (detailed) format. |
| ls -a | List the current directory including hidden files. Hidden files start with "." |
| ls -ld * | List all the file and directory names in the current directory using long format. Without the "d" option, ls would list the contents of any sub-directory of the current. With the "d" option, ls just lists them like regular files. |
Changing File Permissions and Attributes:
You must be the owner of the file/directory or be root before you can do any of these things.
| chmod 755 file | Changes the permissions of file to be rwx for the owner, and rx for the group and the world. (7 = rwx = 111 binary. 5 = r-x = 101 binary) |
| chgrp user file | Makes file belong to the group user. |
| chown trin file | Makes trin the owner of file. |
| chown -R cliff dir | Makes cliff the owner of dir and everything in its directory tree. |
Moving, Renaming, and Copying Files:
| cp file1 file2 | Copy a file. |
| mv file1 newname | Move or rename a file. |
| mv file1 ~/SUBDIR/ | Move file1 into sub-directory SUBDIR in your home directory. |
| rm file1 [file2 ...] | Remove or delete a file. |
| rm -r dir1 [dir2...] | Recursivly remove a directory and its contents. BE CAREFUL! |
| mkdir dir1 [dir2...] | Create directories. |
| mkdir -p dirpath | Create the directory dirpath, including all implied directories in the path. |
| rmdir dir1 [dir2...] | Remove an empty directory. |
Viewing and Editing Files:
| cat filename | Dump a file to the screen in ASCII. |
| more filename | Progressively dump a file to the screen: ENTER = One Line Down / SPACEBAR = Page Down / Q = Quit |
| less filename | Like more, but you can use Page-Up too. Not on all systems. |
| vi filename | Edit a file using the VI editor. All UNIX systems will have VI in some form. |
| emacs filename | Edit a file using the Emacs editor. Not all systems will have Emacs. |
| nano filename | Edit a file using the Nano editor. Not all systems will have Nano. |
| head filename | Show the first few lines of a file. |
| head -n filename | Show the first n lines of a file. |
| tail filename | Show the last few lines of a file. |
| tail -n filename | Show the last n lines of a file. |
A portion of this reference was pulled from Learn UNIX in 10 minutes on FreeEngineer.org.