This article presents the essential commands for Linux. These basic Linux commands will help the novice user to work successfully with Unix systems.

date – show the current date and time
cal – show this month's calendar
uptime – show current uptime
w – display who is online
whoami – who you are logged in as
finger user – display information about user
uname -a – show kernel information
cat /proc/cpuinfo – cpu information
cat /proc/meminfo – memory information
man command – show the manual for command
df – show disk usage
du – show directory space usage
free – show memory and swap usage
whereis app – show possible locations of app
which app – show which app will be run by default

ls – directory listing
cd dir - change directory to dir
cd – change to home
pwd – show current directory
mkdir dir – create a directory dir
rm -r dir – delete directory dir
rm -rf dir – force remove directory dir *
cp -r dir1 dir2 – copy dir1 to dir2; create dir2 if it doesn't exist

ls -al – formatted listing with hidden files
rm file – delete file
rm -f file – force remove file
cp file1 file2 – copy file1 to file2
mv file1 file2 – rename or move file1 to file2 if file2 is an existing directory, moves file1 into irectory file2
ln -s file link – create symbolic link link to file
touch file – create or update file

head file – output the first 10 lines of file
more file – output the contents of file
cat > file – places standard input into file
tail file – output the last 10 lines of file
tail -f file – output the contents of file as it grows, starting with the last 10 lines

ps – display your currently active processes
top – display all running processes
kill pid – kill process id pid
killall proc – kill all processes named proc *
bg – lists stopped or background jobs; resume a stopped job in the background
fg – brings the most recent job to foreground
fg n – brings job n to the foreground

ping host – ping host and output results
whois domain – get whois information for domain
dig domain – get DNS information for domain
dig -x host – reverse lookup host
wget file – download file
wget -c file – continue a stopped download

Install from source:
./configure
make
make install
dpkg -i pkg.deb – install a package (Debian)
rpm -Uvh pkg.rpm – install a package (RPM)

Ctrl+C – halts the current command
Ctrl+Z – stops the current command, resume with fg in the foreground or bg in the background
Ctrl+D – log out of current session, similar to exit
Ctrl+W – erases one word in the current line
Ctrl+U – erases the whole line
Ctrl+R – type to bring up a recent command
!! - repeats the last command
exit – log out of current session

grep pattern files – search for pattern in files
grep -r pattern dir – search recursively for pattern in dir
command | grep pattern – search for pattern in the output of command
locate file – find all instances of file

We hope that the above commands will help a novice user to work quickly and correctly with the Linux system. These commands allow you to work with files and directories, create, delete and output the data you need.