SSH Command in Linux with examples

Show the folder you are in

• $pwdCopy

  Print the full path of the current folder, for example /home/deploy

• $pwd -PCopy

  Print the real path, with any symbolic links resolved

List files and folders

• $lsCopy

  List the names in the current folder

• $ls -lahCopy

  Long list with permissions, owner, human-readable sizes and hidden files

Change folder

• $cd /var/wwwCopy

  Go to an absolute path

• $cd ..Copy

  Go up one level

Create a folder

• $mkdir backupsCopy

  Create one folder

• $mkdir -p projects/site/cssCopy

  Create a whole chain of folders at once; no error if they already exist

Copy files and folders

• $cp report.txt report-backup.txtCopy

  Copy a file

• $cp -r site site-backupCopy

  Copy a folder and everything inside it (-r means recursive)

Move or rename

• $mv old.txt new.txtCopy

  Rename a file

• $mv report.txt /srv/reports/Copy

  Move a file to another folder

Delete files and folders

• $rm temp.txtCopy

  Delete one file

• $rm -i *.tmpCopy

  Ask before each delete

Print a file

• $cat notes.txtCopy

  Print the whole file

• $cat -n script.shCopy

  Print with line numbers

Read a long file page by page

• $less /var/log/syslogCopy

  Open a log; use arrows or Space to move, / to search, q to quit

• $less +F app.logCopy

  Open and follow new lines as they arrive (Ctrl+C to stop following)

Show the last lines

• $sudo tail -n 50 /var/log/nginx/error.logCopy

  Last 50 lines (most files in /var/log need sudo)

• $sudo tail -f /var/log/syslogCopy

  Keep watching new lines as they are added (Ctrl+C to stop)

Simple text editor

• $nano /etc/hostsCopy

  Open a file (use sudo for system files)

Search for text

• $grep "error" app.logCopy

  Lines that contain error

• $grep -i "timeout" app.logCopy

  Ignore capital letters

Find files by name, size or age

• $find /var/www -name "*.php"Copy

  Every .php file below /var/www

• $find . -type d -name "backup*"Copy

  Folders whose name starts with backup

Change permissions

• $chmod 644 index.htmlCopy

  Owner reads and writes; everyone else reads

• $chmod 755 deploy.shCopy

  Everyone can run it; only the owner can change it

Change the owner

• $sudo chown deploy file.txtCopy

  Make deploy the owner

• $sudo chown deploy:www-data file.txtCopy

  Change owner and group together

Run one command as the administrator

• $sudo apt updateCopy

  Run a command as root

• $sudo -iCopy

  Open a root shell (type exit to leave)

Show who you are logged in as

• $whoamiCopy

  Prints your user name

List processes

• $ps auxCopy

  Every process, with owner, CPU and memory

• $ps aux | grep nginxCopy

  Find one program

Live process monitor

• $topCopy

  Live list; press q to quit, M to sort by memory, P by CPU

Stop a process by number

• $kill 1234Copy

  Politely ask process 1234 to stop

• $kill -9 1234Copy

  Force it to stop (last resort)

Manage services

• $systemctl status nginxCopy

  Is it running? Shows recent log lines too

• $sudo systemctl restart nginxCopy

  Stop and start

Read service logs

• $sudo journalctl -u nginxCopy

  Logs of one service

• $sudo journalctl -u nginx -fCopy

  Follow the log live

Free disk space

• $df -hCopy

  Space per disk in human-readable sizes

• $df -hT /Copy

  One filesystem including its type

Space used by folders

• $sudo du -sh /var/logCopy

  Total size of a folder

• $sudo du -h --max-depth=1 /var 2>/dev/nullCopy

  Size of each sub-folder (2>/dev/null hides the errors for folders you cannot open)

Memory use

• $free -hCopy

  RAM and swap in human-readable sizes

Kernel and system

• $uname -aCopy

  Kernel version, host name and architecture

• $uname -mCopy

  Just the architecture (x86_64, aarch64)

Commands you typed before

• $historyCopy

  Numbered list

• $history | grep sshCopy

  Find an earlier command

Network addresses and routes

• $ip aCopy

  Show interfaces and IP addresses

• $ip rCopy

  Show the routing table

Test if a host answers

• $ping -c 4 example.comCopy

  Send four packets and stop

• $ping -c 4 8.8.8.8Copy

  Test the internet without involving DNS

Show listening ports and connections

• $ss -tulpnCopy

  Listening TCP/UDP ports and the program using each (use sudo to see all)

• $ss -t state establishedCopy

  Active TCP connections

Talk to web servers

• $curl https://example.comCopy

  Print the page

• $curl -I https://example.comCopy

  Only the response headers

Log in to a server

• $ssh deploy@203.0.113.10Copy

  Log in as deploy

• $ssh -p 2222 deploy@example.comCopy

  Use a different port

Make a key pair

• $ssh-keygen -t ed25519 -C "me@example.com"Copy

  Create a modern key (recommended)

• $ssh-keygen -lf ~/.ssh/id_ed25519.pubCopy

  Show a key's fingerprint

Copy files over SSH

• $scp report.pdf deploy@example.com:/home/deploy/Copy

  Upload a file

• $scp deploy@example.com:/var/log/app.log .Copy

  Download a file to the current folder

Smart copying and syncing

• $rsync -avz site/ deploy@example.com:/var/www/site/Copy

  Upload only what changed, compressed

• $rsync -avz --progress deploy@example.com:/backups/ ./backups/Copy

  Download with progress

Pack and unpack archives

• $tar -czvf backup.tar.gz /var/wwwCopy

  Create a compressed archive (c = create, z = gzip, v = show files, f = file name)

• $tar -xzvf backup.tar.gzCopy

  Extract it (x = extract)

Debian and Ubuntu

• $sudo apt updateCopy

  Refresh the list of available software

• $sudo apt upgradeCopy

  Install available updates

Print text

• $echo "Hello"Copy

  Print a line

• $echo $HOMECopy

  Print a variable

Read the manual

• $man tarCopy

  The full manual for tar (q to quit)

• $tar --helpCopy

  A shorter summary