The following are a collection of commonly used Unix commands, which students have found useful when dealing with a Unix system or server. This is not a complete list of the commands, nor is it designed to comprehensively cover each command. Rather, it will allow the new Unix user to function in a Unix environment as they learn their way around. (Optional usage is shown in square brackets [] .)
|
Command |
Function |
Example |
Explanation |
|---|---|---|---|
|
ls |
List the files in the current directory. |
ls |
Show me the files in the directory I am currently in. |
|
cat |
Display the contents of a whole file. |
cat myfile |
Show me all of the lines in "myfile", if myfile is longer than 1 screen I will only see the last 20 lines or so. |
|
more |
Display the contents of a file page by page. |
more myfile |
Show me the first page of myfile. To see the next lines touch space bar or the Enter key. To quit type q. |
|
head |
Display the first 10 lines of a file. |
head myfile [head -20 myfile] |
Let me see the first 10 lines of myfile. [Show me the first 20 lines of myfile] |
|
tail |
Display the last 10 lines of a file. |
tail myfile [tail -20 myfile] |
Show me the last 10 lines of myfile. [Like head, show 20 lines.] |
|
grep |
Find a string in a file or files. |
grep 'stuff' afile |
Display all the lines in afile that contain the string "stuff", including lines that have words like stuffy or stuffing. Grep is a very powerful command. |
|
file |
Ask the system to guess what a file contains. |
file myfile |
The system will guess about the contents of a file. If it tells you that the file is a binary, you shouldn't try to display it. |
|
cd |
Change to a different directory |
cd mydir [cd ..] |
Change to the directory "mydir" which is a subdirectory of the current directory. [change to the next higher directory in the tree. The ".." notation is an abbreviation.] |
|
mkdir |
Create a new directory. |
mkdir mydir |
Create a directory called mydir from the current directory |
|
pwd |
Show me the directory I am currently working in. |
pwd |
Shows the current directory. Useful if you want to change to a different directory. |
|
cal |
Display a calendar of the current month, or year. |
cal [cal 2002] |
Display the current month. [Output a calendar for the year 2002.] |
|
date |
Display the current system date and time. |
date |
Show me what day and time it is on the Unix machine I am connected to. |
|
who |
Show me who is logged onto the system and where they are logged in from. |
who |
Shows me the people currently logged onto the system. Useful if I want to talk with them. Shows the login id, not their real name. |
|
w |
Tell me who is logged on and what they are doing. |
w |
A more comprehensive display than who. Shows the login id, as well as what they are doing and how long they have been idle. |
|
finger |
Display information about one or more users. |
finger jl26 |
Displays what the system knows about a user, in this case jl26. Important because it gives the user's real name. |
|
talk |
Establish a 2-way connection between you and another user. |
talk jl26 |
Sets up a two way, online chat session with the user. Both users must be using a recognized terminal type. Exit with ^C. |
|
write |
Send a message to another user. |
write jl26 |
Send a message to a user. In this case jl26. User, (jl26), must be logged into the system for this to work. End message with ^D. |
|
wall |
Send a message to everyone logged onto the system |
wall |
Send a message to everyone logged into the system. This should only be used in extremes. |
|
mesg |
Disable, or enable talking or getting write messages. |
mesg n [mesg y] |
You can stop getting messages, and disable talk by turning off (n) messages. Use y to turn them back on. |
|
stty |
Set up terminal functions and values |
stty erase ^H |
This sets the ^H (backspace) key as the erase key. Use stty with great caution, you can cause your terminal to stop communicating. stty -a shows all the options. BE CAREFUL! |
|
man |
Invoke the online manual |
man man |
Display the online manual page for the "man" command. This is a great tool to see what commands do, and how to use them. |
|
wc |
Count the number of lines, words, and characters in a file. |
wc myfile |
Shows the number of lines, words, and characters, (in that order), in myfile. |
|
exit |
Leave the Unix machine. |
exit |
This will log you off. |