Unix Resources

UNIX commands everyone should know:

ls
List directory's contents
cd
Change directory
Format: cd [dir]
cp
Copy files
Format: cp [path1/source.file] [path2/destination.file]
rm
Remove (or delete)
Format: rm file
mkdir
Make directory
Format: mkdir dir
rmdir
Remove directory:
Format: rmdir dir
chmod
Changes the permission modes of files and directories.
-o change others permission
+ add permission's
r= read
w = write
x = execute
example chmod -o+rx index.html
allows index.html to be read and executed by others
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Very useful, but not neccesary, commands

mv
Move
Format: mv path1/file1 path2/file2
quota
Displays the user's quota (maximum disk space). Some machines have the command myquota.
Format: quota
cat
Concatenate: echos contents of any number of files to the screen.
Format: cat [file1]
grep
Searches files for strings and echoes those entire lines to the screen. To make the search case insensitive, type grep -i. You may use wildcards like * and ? to specify a set of files.
Format: grep [-i] "string" file(s)
head -n
Head: echos first n lines of a file to the screen. The command tail will echo the last lines (default is 10 lines).
Format: head [-n] file
clear
Clear screen
Format: clear
wc
Counts the lines, words and characters in a file.
Format: wc file
ispell
Checks the spelling of words in a file.
Format: ispell file
Format for TeX© files: ispell -t file.tex
whereis
Displays the location of commands.
Format: whereis command

du
Disk usage for the current directory and all subsequent directories. The attribute k (as in du -k) will display the disk usage in kilobytes instead of blocks (1 block = 512 bytes?).
Format: du [-k] [path]
df
Free disk space on current disk.
Format: df [path]
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Other interesting commands:

touch
Create a file. When an existing file is touched, UNIX thinks the file was modified (but it wasn't). This means that if you are programming and 'make' the program, the touched file will be re-compiled.
Format: touch new_file
>
Output redirection (puts output of command into file)
Format: command > file
Redirecting to /dev/null simply ignores the output.
>>
Append (adds the output of command to the end of file)
Format: command >> file
tee
Redirects output of a command to a file AND prints it to the screen. It is useful to think of a pipe leading to a "tee" connection -- one input and two outputs.
Format: command | tee file
who
Lists the login names of everyone currently logged in. For more information on the users logged in, try the command w.
Format: who
date
Displays the current date and time.
Format: date
whoami
Echoes the login name to the screen
Format: whoami
id
Echoes the user and group ID number.
Format: id
file
Finds out what the file format is.
Format: file filename
webster
Online dictionary (not on many machines).
Format: webster word
units
Converts between units
Format: units
write
Sends messages to another user (who is logged on).
Format: write username
nslookup
Looks up the name and IP address of a server.
Format: nslookup servername
apropos
Finds commands that have to do with a keyword. The command man -k does exactly the same thing and is easier to remember.
Format: apropos keyword
source
Executes a file. For instance, source .cshrc will execute the file so that you don't have to login in again if it is changed.
Format: source file
! (bang)
Executes the last command. If a number is specified (e.g. !n) the nth command executed in the session will be repeated. To repeat the last command that started with a certain expression, type !expression.
Format: ![number or expression]
top
Lists the top processes (the ones that are taking the most processor time).
Format: top
<CTRL>z
Suspends current job (program). The job temporarily stops executing, but this is useful because you can execute things at the prompt without quiting the job. Type fg to put the job back in the foreground. Also, you can type bg to make the job continue executing in the background as if you typed an ampersand ("&") at the end of the line when you first executed the job.
bg
Puts a suspended job (job number n) in the background.
Format: bg [n] (NOTE: Here, brackets are needed when specifying a number.)
fg
Brings a job (job number n) to the foreground.
Format: fg [n] (NOTE: Here, brackets are needed when specifying a number.)
jobs
Lists the jobs running in the background.
Format: jobs [-l]
printf
Print formatted output to standard output. This includes numbers and text.
Format: printf "format statement" values
mesg
Allows/denies permission for other users to send you messages.
Format: mesg y/n
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Last modified by CS-GSO, Sunday, 27-Nov-2005 09:10:19 EST