UNIX commands

ls

contents of working directory

mkdir

make a directory, as a subfile of the current directory

cd

change directory to the one indicated

.

refers to the current directory

..

refers to the parent directory

pwd

print working directory - tells you what directors you're in

~

your home directory

cp file1 file2

makes a copy of file1 in the current working directory and calls it file2

rm filename

remove a file

rmdir directoryname

remove directory (has to be empty)

clear

clears terminal screen

cat filename

display the contents of the file on the screen

less

displays contents of the file on the screen, one page at a time

head

writes first 10 lines of the file to the screen

tail

writes last 10 lines of the file to the screen

grep searchterm searchfile

searches specified file for the specified term. multi-word search terms must be in ' '

wc -w filename

counts the words in the file

wc -l filename

counts the lines in the file

cat > file1

reads the keyboard input into another destination - in this case, redirects output to a file called file1. ctrl-d to stop

cat >> file1

append what i type next to the given file. crtl-d to stop

cat file1 file2 > bigfile

concatenates list1 and list2 into a new file called bigfile

<

redirect input -instead of standard (keyboard), can make it from a file

sort < bigfile > newfile

sorts the contents of bigfile and writes them to newfile

who

says who is on the system with you

|

pipe - connect the output of one file directly to the input of another

who | sort

sorts the list of users and prints directly to the screen

who | wc -1

number of users logged in to the system

*

wild card. can use before or after a command - list or list

?

one character wildcard. *ouse will match mouse and house, but not grouse

.c

indicates a file is written in C code. then you can search your directories for stuff that ends in .c

man command

manual page - tells you more about a certain command

whatis command

one line description of the command (less extensive than man)

apropos keyword

is for if you forget how to invoke a specific command. if the keyword is in the command's manual page, it'll show up here.

date

gives you the current date and time

mv name1 name2

changes the name of name1 to name2

diff file1 file2

tells you the difference between the two files. more: http://linux.about.com/library/cmd/blcmdl1_diff.htm

find path expression

finds the given expression located in the given file. more: http://linux.about.com/od/commands/l/blcmdl1_find.htm

tar

creates compressed archives of directories and files, and can also extract directories and files from an archive. more: http://linux.about.com/od/commands/l/blcmdl1_tar.htm

alias new old

assigns an alias to a command. ex. alias ll ls -l makes ls -l happen whenever you type ll

gcc

compile and link

make executablename

makes the executable according to the makefile's instructions

touch

The touch command updates the access and modification times of the named files to the current time and date