Files & Navigation
| Command | Description |
|---|---|
ls |
List directory contents. |
ls -l |
Long format listing. |
ls -la |
Show hidden files as well. |
cd dir |
Change to specified directory. |
cd .. |
Move up one directory level. |
cd ./dir |
Change to a directory within the current location. |
cd ~ |
Go to home directory. |
pwd |
Show current directory path. |
mkdir dir |
Create a new directory. |
rm file |
Delete a file. |
rm -f file |
Force delete a file. |
rm -r dir |
Delete a directory and its contents. |
rm -rf dir |
Force delete a directory recursively. |
cp file1 file2 |
Copy file1 to file2. |
mv file1 file2 |
Rename or move file1 to file2. |
mv file1 dir/ |
Move file to a directory. |
touch file |
Create an empty file or update its timestamp. |
cat file |
View file contents. |
cat > file |
Write standard input to a file (overwrite). |
cat >> file |
Append standard input to a file. |
tail -f file |
Show file contents as it updates (useful for logs). |
System Info
| Command | Description |
|---|---|
date |
Show current date and time. |
uptime |
Show system uptime. |
whoami |
Show current logged-in user. |
w |
Display currently logged-in users. |
cat /proc/cpuinfo |
Display CPU details. |
cat /proc/meminfo |
Display memory details. |
free -h |
Show memory and swap usage. |
du -sh |
Show directory size in human-readable format. |
df -h |
Show disk space usage. |
uname -a |
Show system and kernel details. |
Networking
| Command | Description |
|---|---|
ping host |
Ping a host to check connectivity. |
whois domain |
Get WHOIS information about a domain. |
dig domain |
Get DNS records for a domain. |
dig +x host |
Perform a reverse DNS lookup. |
wget file |
Download a file from a URL. |
wget -c file |
Resume a stopped download. |
wget -r url |
Recursively download an entire site. |
curl url |
Fetch content from a URL. |
curl -o file url |
Save the output of a URL to a file. |
ssh user@host |
Connect to a remote server via SSH. |
ssh -p port user@host |
SSH with a specific port. |
ssh -D user@host |
Connect via SSH and use a bind port. |
Processes Management
| Command | Description |
|---|---|
ps |
Show currently active processes. |
ps aux |
Show all running processes with details. |
kill pid |
Kill a process using its PID. |
killall proc |
Kill all processes by name. |
File Compression & Extraction
| Command | Description |
|---|---|
tar -cf file.tar files |
Create a tar archive. |
tar -xf file.tar |
Extract a tar archive. |
tar -tf file.tar |
Show contents of a tar file. |
Tar Compression Options
| Option | Description |
|---|---|
c |
Create archive. |
t |
List contents. |
x |
Extract archive. |
z |
Use gzip compression. |
j |
Use bzip2 compression. |
f |
Specify filename. |
v |
Show verbose output. |
w |
Ask for confirmation. |
File Permissions
| Command | Description |
|---|---|
chmod octal file |
Change file permissions using octal values. |
chmod 777 file |
Full read/write/execute permissions for all. |
chmod 755 file |
Owner: rwx, Group & Others: r-x. |
Octal Permission Values
| Value | Permission |
|---|---|
4 |
Read (r) |
2 |
Write (w) |
1 |
Execute (x) |
Format: owner/group/world |
Example: chmod 755 file |
Miscellaneous Commands
| Command | Description |
|---|---|
grep pattern file |
Search for a pattern in a file. |
grep -r pattern dir/ |
Search for a pattern recursively in a directory. |
locate file |
Find a file by name. |
whereis app |
Find possible locations of an application. |
man command |
Show the manual page for a command. |