Linux CMDs
ls - The most frequently used command in Linux to list directories
pwd - Print working directory command in Linux
cd - Linux command to navigate through directories
mkdir - Command used to create directories in Linux
mv - Move or rename files in Linux
cp - Similar usage as mv but for copying files in Linux
rm - Delete files or directories
touch - Create blank/empty files
ln - Create symbolic links (shortcuts) to other files
cat - Display file contents on the terminal
clear - Clear the terminal display
echo - Print any text that follows the command
less - Linux command to display paged outputs in the terminal
man - Access manual pages for all Linux commands
uname - Linux command to get basic information about the OS
whoami - Get the active username
tar - Command to extract and compress files in Linux
grep - Search for a string within an output
head - Return the specified number of lines from the top
tail - Return the specified number of lines from the bottom
diff - Find the difference between two files
cmp - Allows you to check if two files are identical
comm - Combines the functionality of diff and cmp
sort - Linux command to sort the content of a file while outputting
export - Export environment variables in Linux
zip - Zip files in Linux
unzip - Unzip files in Linux
ssh - Secure Shell command in Linux
service - Linux command to start and stop services
ps - Display active processes
kill and killall - Kill active processes by process ID or name
df - Display disk filesystem information
mount - Mount file systems in Linux
chmod - Command to change file permissions
chown - Command for granting ownership of files or folders
ifconfig - Display network interfaces and IP addresses
traceroute - Trace all the network hops to reach the destination
wget - Direct download files from the internet
ufw - Firewall command
iptables - Base firewall for all other firewall utilities to interface with
yum, rpm - Package managers depending on the distro
sudo - Command to escalate privileges in Linux
cal - View a command-line calendar
alias - Create custom shortcuts for your regularly used commands
dd - Majorly used for creating bootable USB sticks
whereis - Locate the binary, source, and manual pages for a command
whatis - Find what a command is used for
top - View active processes live with their system usage
useradd and usermod - Add new user or change existing users data
passwd - Create or update passwords for existing users
System/OS-related commands:
To know the OS type: $ uname -o
To check the kernel version: $ uname -r
To get the OS name, release, version: $ cat /etc/os-release
To list the system hardware: $ lshw
To get the CPU details: $ lscpu
To check system memory: $ free -h
To check the virtual memory stats: $ vmstat -S m
To list the mounted disk drives: $ df -fh
To mount the volume:
(Check if the volume is detected)lsblk
(create the directory first to mount volume)$ mkdir -p <Directory Path> $ sudo mount <Src Path>
Find the file (search for a file): $ find -name -print -iname <filename> -print
File the text string from a given directory: $ grep -riln <Search Text> <directory path>
Search the text string in a directory and print the filename containing that string:$ find -type f -print -exec grep <Search Patter> {}\;
User admin Commands
To create a new group: $ sudo groupadd <group name>
Modify existing user, add a user to the group: $ sudo usermod -aG <group name> <User name>
Change the group name: $ sudo groupmod –n <new group name> <old group name>
Search Editor/Text manipulation commands
locate cut uniq sort tee sed
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Network related commands
nmap, check open ports on the server: nmap <IP>
find the IP from fqdn and vice versa: nslookup <IP/FQDN>
lsof, list open files by processes
a) list open files by a specific userlsof -u <Username>
b) find processes running on specific port$ lsof -i TCP:9090
netcat, debug and investigate network
a) start a dummy listening server on port 8080$ netcat -l 8080
b) send data over some port to server$ netcat <remote server ip> <port>
print all listening ports: $ netstat -plunt
get the public ip of the machine: $ curl ifconfig.co
show current routing table: $ route -n
get hostname: $ sudo hostname