ls - List directory contents
ls [options] [file/directory]
cd - Change directory
cd [directory]
pwd - Print working directory
pwd
mkdir - Make directory
mkdir [directory]
rm - Remove files or directories
rm [options] [file/directory]
cp - Copy files or directories
cp [options] source destination
mv - Move or rename files or directories
mv [options] source destination
cat - Concatenate and display files
cat [options] [file]
more - Display output one screen at a time
more [file]
less - Display output one screen at a time, backward as well
less [file]
head - Output the beginning of a file
head [options] [file]
tail - Output the end of a file
tail [options] [file]
grep - Search for patterns in files
grep [options] pattern [file]
chmod - Change file permissions
chmod [options] mode file
chown - Change file ownership
chown [options] user:group file
find - Search for files in a directory hierarchy
find [path] [options] [expression]
tar - Manipulate archives
tar [options] [archive-file] [files...]
df - Report filesystem disk space usage
df [options]
du - Estimate file space usage
du [options] [file/directory]
ps - Report process status
ps [options]
top - Display Linux processes
top
free - Display amount of free and used memory in the system
free [options]
hostname - Show or set the system's host name
hostname [options]
ifconfig - Configure network interface parameters
ifconfig [interface] [options]
ping - Send ICMP ECHO_REQUEST to network hosts
ping [options] host
wget - Retrieve files from the web
wget [options] [URL]
ssh - OpenSSH SSH client
ssh [user@]hostname [command]
scp - Secure copy (remote file copy program)
scp [options] [user@]from-host:source-file [user@]to-host:destination-file
man - Display manual pages
man [command]
info - Display program information
info [command]
passwd - Change user password
passwd [username]
su - Substitute user identity
su [options] [username]
sudo - Execute a command as another user
sudo [options] command
date - Print or set the system date and time
date [options]
cal - Display a calendar
cal [options]
uptime - Show how long the system has been running
uptime
who - Show who is logged on
who [options]
w - Show who is logged on and what they are doing
w [options]
last - Show a listing of last logged in users
last [options]
history - Display the history list with line numbers
history [options]
chmod - Change the mode of a file (permissions)
chmod [options] mode file
chown - Change file owner and group
chown [options] owner[:group] file
uptime - Show how long the system has been running
uptime
wc - Print newline, word, and byte counts for each file
wc [options] [file]
echo - Display a line of text
echo [options] [string]
kill - Terminate processes
kill [options] pid
These commands should cover a wide range of basic Linux tasks and are essential for any Linux user or administrator.