File system
| Command | Purpose |
|---|---|
ls -la | List files with details, including hidden |
cd DIR | Change directory |
pwd | Print working directory |
cp SRC DST | Copy file (-r for recursive) |
mv SRC DST | Move / rename |
rm -rf DIR | Remove recursively, force |
mkdir -p PATH | Create directory tree |
ln -s TARGET LINK | Create symbolic link |
chmod 755 FILE | Set permissions |
chown user:group FILE | Change ownership |
du -sh DIR | Directory size, human-readable |
df -h | Disk free space |
find . -name "*.log" | Find files by name |
Text processing
| Command | Purpose |
|---|---|
cat FILE | Print file |
less FILE | Paginated view (q to quit) |
head -n 20 FILE | First 20 lines |
tail -f FILE | Follow file (like logs) |
grep -rn "text" . | Recursive search with line numbers |
sed -i "s/a/b/g" FILE | In-place substitution |
awk '{print $1}' | First column |
sort | uniq -c | Count occurrences |
wc -l FILE | Count lines |
cut -d, -f1 FILE | First CSV column |
tr a-z A-Z | Translate characters |
Processes
| Command | Purpose |
|---|---|
ps aux | All processes |
top / htop | Interactive process monitor |
kill -9 PID | Force kill |
pkill NAME | Kill by name |
jobs | Background jobs |
nohup CMD & | Run detached |
<cmd> & | Background |
Ctrl+Z / fg / bg | Suspend / foreground / background |
Networking
| Command | Purpose |
|---|---|
ip addr | Show interfaces & IPs |
ss -tulpn | Listening sockets (replaces netstat) |
curl -sSL URL | HTTP request |
wget URL | Download file |
ping HOST | ICMP reachability |
dig NAME | DNS lookup |
ssh user@HOST | Remote shell |
scp FILE user@HOST:/path | Secure copy |
rsync -av SRC DST | Efficient sync |
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