Ten Essential Commands

College of Engineering & CS
Wright State University
Dayton, Ohio 45435-0001

The Ten Most Essential Commands for Unix Users are ls, cd, mkdir, rm, top, ssh, sftp, xterm, emacs and make. So far, you have seen them all except top and make which will be covered soon after the midterm.

Command	Examples
`ls`	`ls -l`	List files, showing all their information.
`ls`	`ls -a`	Show all files (even hidden ones).
`cd`	`cd myFiles`	Change to "myFiles" as the current working directory.
`cd`	`cd -`	Go back to the previous working directory.
`mkdir`	`mkdir XYZ`	Create a new dir named XYZ
`rm`	`rm [filename...]`	Delete the specified files. WARNING: Once deleted, a file CANNOT be recovered! DANGER: On most Unix systems, this command will act without asking for confirmation!
	`rm -r [FILE OR DIRNAME...]`	Remove the given directories and all their contents. WARNING: ALL FILES in these directories will be deleted!
	`rm *`	Delete EVERYTHING in the current directory. If used with "`-r`" this will delete recursively and thus remove directories and their contents too!
`ssh`	`ssh s001xyz@unixapps1`	secure shell login to unixapps1
`sftp`	`sftp s001xyz@unixapps1`	secure FTP
`xterm`		terminal window
`emacs`	`emacs file.txt`	powerful editor
`top`	`TBD`
`make`	`TBD`

Notes

Square brackets ("[]") mean their contents are optional.
An ellipsis ("...") means the previous argument may be repeated
Arguments can usually be combined. For example, grep -ri means do a search that is both case-insensitive and recursive.
Always look in the manpages for more detail!

Here are a few more useful commands.

Command	Summary	Examples
`cat`	Show each file in sequence (concatenate).	`cat [filename...]`	Display the specified files on the screen.
		`cat [filename...] > newfile`	Combine the given files into one file, named "newfile."
`pwd`	Print name of current/working directory.
`cp`	copy files WARNING: If a file is accidentally over-written, it's gone for good!	`cp file1 file2`	Copy "file1" to "file2".
		`cp [filename...] dirname/`	Copy the given filenames into the directory called "dirname".
		`cp -r dir1 dir2`	Copy the directory named "dir1" and all its contents to "dir2".
`mv`	move or rename files WARNING: If a file is accidentally over-written, it's gone for good!	`mv file1 file2`	Rename "file1" to "file2".
		`mv [FILE AND DIRNAME...] destdir/`	Move the given files into "destdir".

CEG 333: Introduction to Unix

Prabhaker Mateti

Ten Essential Commands