Linux Command Line Cheat Sheet
Linux is a free-to-use and freely distributed Unix-like operating system. It is a multi-user, multi-tasking, multi-threaded, and multi-CPU operating system based on POSIX and Unix. It can run major Unix software tools, applications, and network protocols. It supports both 32-bit and 64-bit hardware. Linux inherits the network-centric design philosophy of Unix and is a stable multi-user network operating system.
System
| uname | Display Linux system information |
| uname -r | Display kernel version information |
| uptime | Display how long the system has been running (including load average) |
| hostname | Display system hostname |
| hostname -i | Display the IP address of the system |
| last reboot | Display system reboot history |
| date | Display current system date and time |
| timedatectl | Query and change the system clock |
| cal | Display the current calendar month and date |
| w | Display users currently logged into the system |
| whoami | Display who you are logged in as |
| finger username | Display information about a user |
Hardware
| dmesg | Display boot messages |
| cat /proc/cpuinfo | Display more info about CPU (e.g., model, name, cores, vendor) |
| cat /proc/meminfo | Display more info about memory (e.g., total and free memory) |
| lshw | Display info about system hardware configuration |
| lsblk | Display block device information |
| free -m | Display free and used memory (-m flag for MB) |
| lspci -tv | Display PCI devices in a tree diagram |
| lsusb -tv | Display USB devices in a tree diagram |
| dmidecode | Display hardware info from BIOS |
| hdparm -i /dev/xda | Display info about disk data |
| hdparm -tT /dev/xda | Perform read speed test on device xda |
| badblocks -s /dev/xda | Test for unreadable blocks on disk |
Users
| id | Display active user details (uid, gid, groups) |
| last | Display last logins in the system |
| who | Display who is logged into the system |
| groupadd “admin” | Add group “admin” |
| adduser “Sam” | Add user Sam |
| userdel “Sam” | Delete user Sam |
| usermod | Change/modify user information |
Files
| ls -al | List files - including regular, hidden and their permissions |
| pwd | Show current directory path |
| mkdir ‘dir_name’ | Create a new directory |
| rm file_name | Delete a file |
| rm -f filename | Force delete a file |
| rm -r dir_name | Recursively delete a directory |
| rm -rf dir_name | Force and recursively delete a directory |
| cp file1 file2 | Copy content of file1 to file2 |
| cp -r dir1 dir2 | Recursively copy dir1 to dir2 (creates dir2 if not exist) |
| mv file1 file2 | Rename file1 to file2 |
| ln -s /path/to/file link_name | Create a symbolic link to file_name |
| touch file_name | Create a new file |
| cat > file_name | Create a file from keyboard input |
| more file_name | Output file content |
| head file_name | Display first 10 lines of file |
| tail file_name | Display last 10 lines of file |
| gpg -c file_name | Encrypt a file |
| gpg file_name.gpg | Decrypt a file |
| wc | Print byte, word, and line counts of a file |
| xargs | Execute commands from standard input |
Processes
| ps | Display currently active processes |
| ps aux | grep ’telnet' | Search for process id of ’telnet' |
| pmap | Display memory map of a process |
| top | Display all running processes |
| kill pid | Terminate process with given pid |
| killall proc | Kill/terminate all processes named proc |
| pkill proc-name | Send signal to process by name |
| bg | Resume a suspended job in the background |
| fg | Bring a background job to the foreground |
| fg n | Bring job n to the foreground |
| lsof | List files opened by processes |
| renice 19 PID | Run process with very low priority |
| pgrep firefox | Find Firefox process ID |
| pstree | Visualize processes in a tree model |
File Permissions
| chmod octal filename | Change file permissions to octal |
| chmod 777 /data/test.c | Set rwx permissions for owner, group, and everyone |
| chmod 755 /data/test.c | Set rwx for owner, r-x for group and everyone |
| chmod 766 /data/test.c | Set rwx for owner, rw- for group and everyone |
| chown owner user-file | Change file ownership |
| chown user:group file_name | Change owner and group owner of a file |
| chown user:group dir_name | Change owner and group owner of a directory |
Network
| ip addr show | Display IP addresses and all network interfaces |
| ip address add 192.168.0.1/24 dev eth0 | Assign IP 192.168.0.1 to interface eth0 |
| ifconfig | Display IP addresses of all network interfaces |
| ping host | Send ICMP echo requests to establish connection |
| whois domain | Retrieve info about a domain name |
| dig domain | Retrieve DNS info for a domain |
| dig -x host | Perform reverse lookup on a domain |
| host google.com | Perform IP lookup for a domain name |
| hostname -i | Display local IP address |
| wget file_url | Download a file from an online source |
| netstat -pnltu | Display all active listening ports |
Compression/Packaging
| tar -cf home.tar home | Create archive ‘home.tar’ from ‘home’ |
| tar -xf files.tar | Extract archive ‘files.tar’ |
| tar -zcvf home.tar.gz folder | Create a compressed tar archive from folder |
| gzip file | Compress file into .gz extension |
Installing Packages
| rpm -i pkg_name.rpm | Install rpm package |
| rpm -e pkg_name | Remove rpm package |
| dnf install pkg_name | Install package using dnf tool |
Install from Source (Compile)
| ./configure | Check system for required software to build program |
| make | Compile the source |
| make install | Install binaries to default/modified path |
Search
| grep ‘pattern’ files | Search for a pattern in files |
| grep -r pattern dir | Search recursively for a pattern in a directory |
| locate file | Find all instances of a file |
| find /home/ -name “index” | Find files starting with ‘index’ in /home |
| find /home -size +10000k | Find files larger than 10000k in home |
Login
| ssh user@host | Securely connect to host as user |
| ssh -p port user@host | Securely connect to host using specific port |
| ssh host | Securely connect via default SSH port 22 |
| telnet host | Connect to host via default telnet port 23 |
File Transfer
| scp file1.txt server2:/tmp | Securely copy file1.txt to server2 in /tmp dir |
| rsync -a /home/apps /backup/ | Sync contents of /home/apps to /backup |
Disk Usage
| df -h | Display free space on mounted systems |
| df -i | Display free inodes on filesystems |
| fdisk -l | Display disk partitions, sizes and types |
| du -sh | Display disk usage of current directory in human-readable format |
| findmnt | Display target mount points for all filesystems |
| mount device-path mount-point | Mount a device |
Directory Traversal
| cd .. | Move up one level in directory tree |
| cd | Change to $HOME directory |
| cd /test | Change to /test directory |