10 Must-Know Linux Commands

1. cd, pwd, ls — navigation

pwd            # where am I?
cd /var/log    # go here
ls -la         # list everything, including hidden files

2. grep — find text

grep -R "TODO" src/          # search folder recursively
grep -i error app.log        # case-insensitive

3. find — find files

find /var/log -name "*.log" -mtime -7   # log files modified in the last week
find . -type d -name "node_modules"     # find all node_modules folders

4. less — read big files without loading them

less huge.log
# / to search, n for next, q to quit

5. tail -f — live-follow a log

tail -f /var/log/nginx/access.log

6. top / htop — see what's using resources

htop is friendlier; install if missing.

7. ps aux | grep <name> — find a process

ps aux | grep nginx

8. kill — stop a process

kill 1234           # nice signal
kill -9 1234        # force

9. curl — talk to any HTTP endpoint

curl -sS https://api.github.com/repos/kubernetes/kubernetes | head
curl -X POST -H "Content-Type: application/json" -d '{"x":1}' https://api.example.com/echo

10. ssh and scp — remote work

ssh you@server
scp file.tar.gz you@server:/tmp/

Bonus: !! and !$

sudo !!        # re-run the previous command with sudo
mv file.txt !$ # last argument of previous command

Learn these ten commands well and 90% of everyday Linux work becomes muscle memory.