Top 10 Linux Commands Every DevOps Engineer Must Know in 2024

ls              # show files/folders in current directory
ls -l           # detailed view: permissions + owner + size + date
ls -a           # show hidden files (starting with .)
ls -lh          # human readable file sizes`

cd /var/log     # move to log directory
cd ~            # go to home directory
cd -            # go to previous working directory
cd ../          # go up one level

grep "error" /var/log/syslog          # find word "error"
grep -i "failed" auth.log             # case-insensitive search
grep -R "DATABASE_URL" .              # recursive search in folders
# Filtering running processes
ps aux | grep nginx                   # find nginx processes

cat /etc/os-release                   # view entire file at once
less /var/log/messages                # scroll a long file
tail -n 100 app.log                   # last 100 lines
tail -f /var/log/nginx/access.log     # live log stream for debugging

chmod +x deploy.sh                    # give execute permission
chmod 600 id_rsa                      # secure SSH private key
# Change ownership to nginx user
chown www-data:www-data /var/www/app -R

top        # show CPU, memory usage, running processes
htop       # interactive UI (requires installation)

df -h                           # show mounted filesystems usage
du -sh *                        # size of each item in folder
du -sh /var/log/*               # find large log files

curl -I https://google.com      # only response headers
curl -X POST https://api.local/endpoint \   -H "Content-Type: application/json" \   -d '{"msg":"ping"}'           # API request with data
wget https://file.com/app.zip   # download file

tar -czvf backup.tar.gz /data   # create compressed
tar tar -xzvf backup.tar.gz         # extract tar.gz backup
zip -r project.zip folder/      # zip folder
unzip project.zip               # unzip

systemctl status nginx          # service status
systemctl restart docker        # restart a service
systemctl enable nginx          # auto-start on boot
systemctl stop nginx            # stop service