| Purpose | Commands | Example/Explanation |
| Help and Options |
| show service options | man service_name | man sudo |
| Help command or service | service_name --help | man --help |
| recuresive | -r | rm -r example.txt |
force to do something.
Ignore any prompt when deleting a write-protected file. | -f | rm -f example.txt |
| Clear screen | clear | |
| show command history | history
history | grep ufw
history | sort -rn | |
| System, Process and Services |
| shutdown the system | shutdown -r now | |
| reboot /restart | reboot
init 6 | |
| show process for users or all | ps -option | ps -u, ps -aux |
| To find the IP address | ip a | |
| see Linux servers resource usage | top | top |
| Kill process | kill pid | kill 16750, kill -9 16750 (by force) |
| Show machine date and time | date | date |
| Set time zone | sudo timedatectl set-timezone zone_name | sudo timedatectl set-timezone Asia/Dhaka |
| access remote server using SSH | ssh -p 22 user@IP_ADDRESS | ssh -p 22 user@10.10.18.215 |
| version check | hostnamectl | |
| show all services | service --status-all | |
| service status/start/stop | systemctl status/start/stop service_name | systemctl status ssh |
| show disk space / disk file system | df -HT | df -HT |
| show FIle and Folder wise space | du -sh *|less | du -sh *|less |
| exporting environment variables in runtime | export variable_name=value | export MY_PROJECT_PATH=/opt/project/techecosys |
| Show all environment variable | env | show all existing variables |
| show individual variable | echo $VARIABLE_NAME | echo $MY_PROJECT_PATH |
| set another name for a command | alias lsl="command" | alias lsl="ls -l", alias dpa="docker ps -a" |
| Search location of any command | whereis command_name | whereis sudo, whereis ls |
| See what a command actually is | whatis command_name | whatis sudo, whatis ls |
| Unzip zip file | unzip filename.zip -d /path/ | unzip website.zip -d /var/www/html/ |
| File and Directory - Wildcard |
| show present directory | pwd | |
| | | |
| create directory | mkdir folder_name | mkdir dir1 dir2 |
| change directory | cd dirtory_path | cd dir1 |
| create file | touch options file_name | touch -m example1.txt example2.txt index.html |
| Create A File With content | cat filename | cat foo.txt -> Type content -> press ctrl + d |
| To view a file content | cat filename | cat foo.txt |
| To Append/update Text File content | cat >>filename | cat >>foo.txt |
| show all files and folders | ls -l | ls -l |
| show all .txt files using Wildcard | ls -l *.txt | * is wildcard which match pattern |
| view BIG file content more/less | cat file_name | more or less | cat /etc/passwd | more |
| copy file/Files in Linux | cp source destination | cp dir1/foo.txt dir2 |
| move file one directory to another | mv source destination | mv dir1/foo.txt dir2 |
| remove file | rm options file_name | rm -rf test.txt |
| remove all files which are .txt | rm *.txt | |
| Copy or duplicate dir | cp [options] source destination | cp [options] source destination |
| remove folder | rm -option folder_name | rm -d folder_name - empty
rm -r folder_name - nonempty |
| big file content view | head file_name or tail file_name | head foo.txt |
| To search for matching patterns in a file | grep [OPTION...] PATTERNS [FILE...] | grep -i "UNix" example.txt |
| Find file/folder name | find [path] [options] [expression] | find /test/ -type f -name "*.txt"
find /path/to/search -type d -name "docs" |
| Users, Grups and Permission |
| Show all users | awk -F':' '{ print $1}' /etc/passwd | Awk prints every line of data from the specified file |
| add user with home directory | sudo useradd -m username | sudo useradd -m saidul |
| set/modify password | passwd username | passwd saidul |
| Switch User | su - username | su - username |
| show user group | groups username | |
| Add user to a group | sudo usermod -aG groupname username | usermod -aG sudo gkerp |
| change file permissions | sudo chmod options file_name | chmod +x foo.txt |
| granting ownership of files or folders | chown | chmod saidul:saidul foo.txt |
| | | |
| vim/vi commands |
| view file content | vi filename | |
| insert | press i | |
| | :q - quit, :wq - write and quit | |
| Network |
| Display network interfaces and IP addresses | ifconfig | this command shows all network info |
| Trace all the network hops to reach the destination | traceroute HOST | traceroute localhost |
| Direct download files from the internet | wget | |
| Firewall command | ufw allow/status/disallow | ufw allow 80 |
| Base firewall for all other firewall utilities to interface with | iptables | |
| | | |
| Package | | |
| Update the local package index | sudo apt update | |
| Install a new package. | sudo apt install [package] | sudo apt install traceroute |
| Uninstall a package. | sudo apt remove [package] | sudo apt remove traceroute |
| Upgrade all packages | sudo apt upgrade | |
| Remove all packages that were installed automatically as dependencies and are no longer required. | sudo apt autoremove | |
| | sudo apt autoclean | |
| Purge is identical to remove except that packages are removed and purged (any configuration files are deleted too). | sudo apt-get remove <package-name> | |
| | | |
Md Saidul Haque 
