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Linux Commands Cheat Sheet by

The essential Linux commands for files, permissions, networking, processes, and package management — with syntax and the flags you'll actually use. Handy for CompTIA Linux+ prep, sysadmin work, and daily terminal life. More free study resources at bytebarhq.com.

Navigation & Files

pwd
Print working directory
 
ls -la
List all files incl. hidden, with details
 
cd -
Jump back to previous directory
 
cp -r src dst
Copy recurs­ively
 
mv old new
Move / rename
 
rm -rf dir
Delete recurs­ively, no prompt (⚠️ careful)
 
mkdir -p a/b/c
Create nested direct­ories
 
touch file
Create empty file / update timestamp
 
find / -name "­*.l­og"
Search by name
 
grep -r "­err­or" /var/log
Search inside files, recursive
 
cat / less / head / tail
View files (
tail -f
follows live)
The 40+ commands CompTIA Linux+, Security+, and every sysadmin interview expect.

Permis­sions

ls -l
Show permis­sions (
-rwxr-xr--
)
 
chmod 755 file
rwx / r-x / r-x — standard for scripts
 
chmod 644 file
rw- / r-- / r-- — standard for files
 
chown user:group file
Change owner
 
sudo !!
Re-run last command as root
Numeric recap: 4 = read, 2 = write, 1 = execute → 7 = rwx, 6 = rw-, 5 = r-x, 4 = r--

Networking

ip a
Show interfaces + IPs (modern 
ifconfig
)
 
ip r
Show routing table
 
ping -c 4 host
Test connec­tivity
 
ss -tulpn
Listening ports + processes (modern 
netstat
)
 
curl -I host
Fetch headers
 
dig +short exampl­e.com
DNS lookup
 
traceroute host
Path packets take
 
ssh user@host
Secure remote shell
 
scp file user@h­ost­:/path
Secure copy
Modern replac­ements: 
ip
for 
ifconfig
, 
ss
for 
netstat
.

System & Processes

ps aux | grep nginx
Find processes
 
top
/ 
htop
Live process monitor
 
kill -9 PID
Force-kill a process
 
systemctl status nginx
Service status
 
systemctl restart nginx
Restart a service
 
journalctl -u nginx -f
Follow service logs
 
df -h
Disk space (human­-re­adable)
 
du -sh *
Directory sizes
 
free -h
Memory usage
 
uptime
Load + uptime
 
uname -a
Kernel / system info
 
-h
means human-­rea­dable — use it for df, du, free.

Text Power Tools

grep -i "­fai­l" log
Case-i­nse­nsitive search
 
sort file | uniq -c
Count unique lines
 
awk '{print $1}' file
Print column 1
 
sed 's/old­/new/g' file
Find and replace
 
wc -l file
Count lines
 
history | grep ssh
Search command history
Chain them with pipes — that's where the power is.

More from ByteBar

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Added More from ByteBar footer block with study guide CTA link.
 

Metadata

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  • Published: 14th September, 2026
  • Last Updated: 22nd October, 2026

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