Everyday Linux Commands

June 8, 2022 · 6 min read

I use these Linux commands over and over in daily work, so rather than searching for them every time, I've organized them into a quick-reference note. They're grouped by CPU, memory, files, and system, with a list of frequently used commands at the end.

CPU Commands

# Number of physical CPUs
grep 'physical id' /proc/cpuinfo | sort -u | wc -l

# Number of CPU cores
grep 'core id' /proc/cpuinfo | sort -u | wc -l

# Number of CPU threads
grep 'processor' /proc/cpuinfo | sort -u | wc -l

# CPU model
dmidecode -s processor-version

# Detailed CPU information
cat /proc/cpuinfo

Memory Commands

# Current memory usage
free -h

# Top 10 processes by memory usage
ps aux | head -1;ps aux |grep -v PID |sort -rn -k +4| head -10

File Commands

ls        # show files or directories
ls -l     # list files with details (list)
ls -a     # list all files and directories in the current directory, including hidden ones (all)
mkdir     # create a directory
mkdir -p  # create a directory, creating parent directories as needed (parent)
cd        # change directory
touch     # create an empty file
echo      # create a file with content
cat       # view file contents
cp        # copy
mv        # move or rename
rm        # delete a file
rm -r     # delete recursively, including subdirectories and files
rm -f     # force delete
find      # search the filesystem for a file
wc        # count lines, words, and characters in text
grep      # search for a string in a text file
rmdir     # delete an empty directory
tree      # show a directory as a tree; requires the tree package
pwd       # show the current directory

System Commands

# Show system information
lsb_release -a

# Query the kernel version
uname -r

Frequently Used Commands

cd: change the current working directory
ls: list files and subdirectories in the current working directory
mkdir: create a new directory
rm: delete files or directories
cp: copy files or directories
mv: move files or directories
touch: create a new file or update an existing file's access and modification times
cat: view file contents
grep: search for a specific string in files
find: locate files in the filesystem
chmod: change file or directory permissions
chown: change file or directory ownership
top: show the processes currently running on the system
ps: list currently running processes
ssh: connect to a remote host over a secure shell
scp: copy files between hosts over a secure shell
tar: create or extract tar archives
gzip: compress files
unzip: decompress files
ping: test network connectivity to another host
ifconfig: show and manage network interfaces
route: show and manage the network routing table
netstat: show network status information
iptables: manage firewall rules
systemctl: manage system services
service: manage system services
du: show disk usage of directories and files
df: show filesystem disk usage
uname: show system information
date: show or change the system date and time
history: show the history of previously executed commands
man: view a command's manual page
which: find the path of a given command
whereis: find the path and manual page of a given command
whoami: show the current user's username
su: switch to another user or the superuser
sudo: run a command with superuser privileges
ssh-keygen: generate an SSH key pair
ssh-copy-id: copy an SSH public key to a remote host
scp: securely copy files over SSH
curl: send requests to a server and fetch the response
wget: download files from the web
vim: a powerful text editor
nano: an easy-to-use text editor
tar: create or extract tar archives
gzip: compress files
bzip2: compress files
unzip: decompress files
zip: create or extract zip archives
sshfs: mount a remote filesystem over SSH
rsync: sync files and directories remotely
awk: process and analyze text
sed: process and transform text
sort: sort lines of text
uniq: remove duplicate lines from text
cut: extract columns from text
paste: merge text columns into a single file
tee: copy standard output to a file and the terminal
diff: compare the differences between two files
patch: apply a patch from a diff file
head: show the first lines of a file
tail: show the last lines of a file
tar: create or extract tar archives
gzip: compress files
bzip2: compress files
unzip: decompress files
zip: create or extract zip archives
rpm: install, remove, and query RPM packages
dpkg: install, remove, and query Debian packages
ps: list running processes
kill: stop a running process
top: show the processes currently running on the system
uptime: show system uptime and load
free: show system memory usage
df: show filesystem disk usage
du: show disk usage of directories and files
mount: mount a filesystem
umount: unmount a filesystem
chroot: change the root directory
ln: create symbolic or hard links
echo: print text or variables
export: set environment variables
source: execute a script and import it into the current shell
alias: create an alias
unalias: remove an alias
jobs: list currently running jobs
bg: send a job to run in the background
fg: bring a job back to the foreground
nohup: run a job in the background so it survives closing the terminal
crontab: set up scheduled tasks
at: run a command at a specified time
screen: create multiple terminal sessions
tmux: create multiple terminal sessions
curlftpfs: mount a remote filesystem over FTP
dig: query DNS servers
nslookup: query DNS servers
ping: test network connectivity to another host
traceroute: show the path packets take through the network
tcpdump: capture network packets
iftop: show network traffic information

Wrapping Up

Nobody remembers every command — what matters is knowing where to look them up. This note collects the commands I use most, grouped by CPU, memory, files, and system, and together with the man pages it covers most troubleshooting scenarios. As new commands worth recording come up, I'll keep adding them here.

CPU Commands​

Memory Commands​

File Commands​

System Commands​

Frequently Used Commands​

Wrapping Up​