cp source destination |
Copies the source file to destination. |
ls |
Listsd the content of the current directory. ls -l – shows also extra info. ls -R – shows content of directory and also subdirectories. ls -m – displays the content in comma sepparated. |
mv source destination |
Moves source to destination (if a directory, else it renames source to destination) |
cd directory |
Changes the current directory. cd ~ – will change the path to the root of the user. cd / – changes the path to the root of the filesystem. cd .. – changes the path to the directory above. |
pwd |
Displays the current directory |
mkdir directory |
Creats a new directory. |
rm -R directory |
Deletes a directory including subdirectories. The user will be promoted for each read-only file. |
rm -Rf directory |
Deletes a directory including subdirectories. The user will NOT be promoted for each read-only file. |
rm directory |
Deletes a file. |
chmod entity+mode+permission file/directory |
Changes the mode of the file in terms od permissions. Entiry= u (for user), g (for group), o (for other), a (for all). Mode = + (for adding permissions) or – (for removing permissions). Permissions= r (for read), w (for write), x (for execute). Example: chmod g+w-r test_file.txt – this adds the write permission to the group but removes the read permission. |
chmod user permission_group+group permission_group+all permission_group file/directory |
Sets the permission for the file, where permission_groups is a number 0-7 which represents a group of permissions – 1-execute, 2-write, 4-read, Example: chmod 765 test_file.txt – this will let the user full permissions to the file but only write+read permission to the group and only read permission for all the rest. |
find . –name file name pattern |
Searchs for file by name, from the current path recursivly. |
grep -l text file_pattern |
Finds all the files which contain the text. Example: grep -l “case” *.java – finds all the java files which contain the word ‘case’. |
cmp file file |
Compares 2 files. Determines whether the files are identical. |
diff file/directory file/directory |
Finds all the diffrences between 2 files or directories. |
head file |
Displays the first 10 lines of a file. head -3 file – displays the first 3 lines of a file. |
tail file |
Displays the last 10 lines of a file. tail -3 file – displays the last 3 lines of a file. |
nl file |
displays the file content with numbered lines. |
sort file |
displays the file content with sorted lines. |
strings file |
Shows only the readable strings of a file. |
wc file |
Displays the number of lines, words and bytes of a file. |
file file |
Gives information about a file. |
cat file1 file2 |
Attaches the 2 files one after another. |
more filename |
Displays a file with paging. |
pr -dp |
Prints a file with paging. pr has a lot of other format abilities. |
od binary filename |
display binary files as eqivalent octal/hex codes |
tar -cvf tar file file1 to be compressed file2 to be compressed file3 t… |
Compress files into an tar archive. |
tar -xpvf tar file |
Uncompress a tar file. |
tar -tf file |
Lists the contents of a tar archive. |
gzip file |
Compress a single into a gz archive. |
gunzip |
Decompress a single gz archive. |
gzcat filename |
Prints the contents of a zipped file. |
df |
Shows disk space information. |
quota -v |
Finding out your available disk space quota |
uname -a |
Gives information about the current system. |
du |
Prints the size on disk of each directory and file. |
iostat -xtc |
Shows the devices(disk/cpu) usage. |
top |
show system stats and top CPU using processes |
uptime |
show one line summary of system status |
passwd |
Changes user password. |
write user [terminal] |
Send messges to another user. If no terminal is entered than a list of current used terminals is displayed to choose from. |
w |
Shows who is logged in and what is running. |
who |
Finding out who’s logged on |
finger |
Shows who is logged in. finger name – shows info on user. |
whoami |
who is logged onto this terminal |
telnet address |
Connect to a remote machine. |
ssh |
Connect to another machine. |
ps -a |
Shows all current processes. |
kill process id |
Kills a process. |
kill -9 process id |
Kills a process by force. |
jobs |
A list of current jobs numbered. |
fg job number |
Brings a job to the forground. |
bg job number |
Brings a job to the background. |
kill %job number |
Kills a job. |
command & |
Runs the command in the background |
CTRL-C |
Stops a process. |
CTRL-Z |
Stops a process temporery. |
whereis unix_command |
Displays the path to a unix command source, binaries and manual page. |
command1 | command2 |
runs command1 and direct it’s output to command2 as input. Example: ls | grep “java” |
command1 ; command2 |
Runs command1 and than runs command2 |
command1 || command2 |
Runs command1 and if it fails, runs command2 |
command1 && command2 |
Runs command1 and if it succeeds, runs command2 |
command > file path |
Writes the output of a file into a file. |
man command |
A command manual. |
alias name “command“ |
Creates a new command alisas. Example: alias lj “ls -R | grep java” – this creats a new command ‘lj’ that prints all the java files in the subdirectories. |
history |
list of previously executed commands |
command | at -m time. |
executes command at a time in the future. Example: ( ls > ls.txt ) | at -m 08:02 -> this will create a file containg the contents at exactly 08:02. at -l will print the list of schedualed commands. |
script file |
Starts a script that records all you type into a file. To stop the script press ctrl-d. |
date |
show date and time |