Info - Basic Unix Commands

cd | pwd | ls | cat | mkdir | rmdir | cp | mv | rm | grep | tar | zip | unzip | compress | uncompress


Introduction
This guide is intended as a basic reference sheet for beginning Unix users. It does not expand into the functionality of Unix, but will give you the commands necessary to move around within the Unix environment, create and remove files, and organize your files into directories. After you have mastered all of these skills and get comfortable with the O/S, further Unix commands will be within reach. Remember that all of these commands are CASE SENSITIVE.

Creating and Editing a File
The first thing you need to understand about Unix is that the files it deals with come in many different forms. These files could be bits of saved e-mail, articles, or just files that you created with an editor (which is like creating a document with a word processor). Other files are created by certain programs in Unix, such as Elm or Pine, and are used to configure those programs correctly. Finally, there are system files that are needed for your account to function and should never be removed.

To create a file, you need to use a text editor. Two common Unix text editors are Vi and Pico. Each of these text editors has on-line documentation pages which we will address later in this tutorial. Vi is a powerful editor with a fair amount of documentation, but is very cumbersome and complex to learn. Pico is much easier to learn but is far less powerful and less documented. For beginners, Pico is recommended because the added functionality of Vi isn't needed until you become a more experienced Unix user, it is essential for shell programming.

cd [directory]

 

The cd command changes your current working directory to the directory you specify.

pwd

 

The pwd command prints your current (or present) working directory.

 

Usage: Simply type "pwd" and hit return to display your current working directory.

ls [directory]

 

The ls command lists the files and subdirectories in the directory you specify. If not directory is specified, a list of the files and subdirectories in the current working directory is displayed.

 

Usage: The ls command will display all files in the current working directory - simply type "ls" and hit return. You can also add some additional arguments to customize the list display.

 

If you type "ls -F" it will append a forward slash to the subdirectory names so you can easily distinguish them from file names.

 

If you type "ls -a" it will show all "hidden files". Hidden files begin with a ".", i.e. ".htaccess" files.

 

If you type "ls -l" it will show detailed information about each file and directory, including permissions, ownership, file size, and when the file was last modified.

 

You can mix the arguments, i.e. if you type "ls -aF" you will see a list of all file names (including hidden files and a forward slash will be appended to directory names.

cat [filename]

 

The cat command displays the contents of the filename you specify. If you want to display the file one screen at a time try "cat [filename] | more" or simply "more [filename]" (you've probably done this at a DOS prompt- "type [filename] | more").

mkdir [directory]

 

The mkdir command makes a new directory with the name, directory, that you specify. Simply type "mkdir [directory name]" and hit return.

rmdir [directory]

 

The rmdir command removes the directory that you specify. Simply type "rmdir [directory name]" and hit return.

cp [source-file] [target-file]

 

The cp command copies a source-file to a target-file. Simply type "cp [source-file] [target-file]" and hit return. You can specify pathnames as part of the file specification. If target-file exists then it is overwritten.

mv [source-file] [target-file]

 

The mv command renames a file or moves it to a new location. Simply type "mv [source-file] [target-file]" and hit return. You can specify pathnames as part of the file specification. If target-file exists then it is overwritten.

rm [filename]

 

The rm command deletes (removes) a file. Simply type "rm [filename]" and hit return. You can specify pathnames as part of the file specification.

grep [pattern] [filenames]

 

The grep command finds lines in files that match specified text patterns. Simply type "grep [pattern] [filenames]" and hit return. You can specify pathnames as part of the file specification. For example if you want to search for a pattern "gif" in all html files in your current working directory, you would type "grep gif *.html" and hit return. The grep command would then list all occurrences of "gif" it finds in .html files in the current working directory.

tar [options] [tarfile] [files]

 

The tar command copies a file or files to or from an archive. To put all the files in a directory into one tar format file, simply type "tar cvf tarfile directory" at a telnet command prompt and replace tarfile with the name you want to call your archived file, and replace directory with the name of the directory that contains the files you want to tar.

 

To extract the files from a tar format archive, simply type "tar xvf tarfile at a telnet command prompt and replace tarfile with the name of the archived file you are extracting.

 

For example, you could type tar cvf pages.tar htdocs" at a telnet command prompt to archive the files in the htdocs directory to a tar format file called pages.tar.

 

To view the contents of the pages.tar tarfile without extracting them, type "tar tvf pages.tar". This will display all files that are included in the tar archive.

 

You could also type "tar xvf pages.tar" at a telnet command prompt to extract into the current directory the files in the archive pages.tar.

zip [options] [zipfile] [files]

 

The zip command compresses a file or list of files into a zip format archive file. This command is compatible with pkzip on a PC. Simply type "zip zipfile file1 file2 file3" at a telnet command prompt and replace zipfile with the name you want to use for your compressed zip archive file, and replace fileX with the name of the file(s) you want to compress into the zip archive.

 

For example, type "zip backup.zip home.html index.html" at a telnet command prompt to compress and archive the files called home.html and index.html into the file called backup.zip.

unzip [options] [zipfile]

 

The unzip command extracts a zip format archive file. This command is compatible with pkunzip files from a PC. Simply type "unzip zipfile" at a telnet command prompt and replace zipfile with the name of your zip format archive file.

 

For example, type "unzip -aL old.zip" at a telnet command prompt to extract files contained in the archive called old.zip. The "-aL" are options that are generally useful when unzipping files created on a PC.

compress [files]

 

The compress command shrinks a file or files into compressed versions to save space on your Virtual Server. This command is good for you to use on your log files when they get very large. Simply type "compress filename(s)" at a telnet command prompt and replace filename(s) with the name of your files you want to compress.

 

For example, type "compress access_log agent_log" at a telnet command prompt to compress the access_log and agent_log files. The compressed files will then be access_log.Z and agent_log.Z.

uncompress [files]

 

The uncompress command expands a compressed file or set of compressed files. Simply type "uncompress filename(s)" and hit return.