These commands are the most commonly used and are a good starting point for learning the Linux command line.
ls – list files and directories
cd – change directory
pwd – print working directory
mkdir – make directory
rmdir – remove directory
touch – create a new file
cp – copy a file or directory
mv – move or rename a file or directory
rm – remove a file or directory
chmod – change file permissions
chown – change file ownership
sudo – run a command with superuser privileges
su – switch to another user
top – display system processes
ps – display process status
kill – terminate a process
df – display disk usage
du – display file space usage
free – display memory usage
echo – print a message
cat – concatenate and display files
less – display text file contents one page at a time
head – display the first lines of a file
tail – display the last lines of a file
grep – search for a pattern in text
find – find files by name or other criteria
locate – quickly find files by name
which – display the path of a command
whereis – locate the binary, source, and man page files of a command
man – display the manual page of a command
apropos – search the manual page descriptions
info – display information about a command
history – display command history
clear – clear the terminal screen
date – display the current date and time
time – measure the time taken by a command
cal – display a calendar
bc – perform calculator operations
yes – repeatedly output a string
no – do nothing
alias – create a short name for a command
unalias – remove a command alias
env – display environment variables
export – set an environment variable
source – execute commands from a file
. – execute commands from a file
exit – terminate the current session
logout – terminate the current session
reboot – reboot the system
shutdown – shut down the system