Linux Shell Commands
Essential Linux / Unix shell commands — file system, text processing, processes, networking.
Reference
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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