Important Linux Commands

Process based Commands

Killing process with partial name

$ pkill -f <partial_name>

Listing all the process

$ ps -e 

Package Based Commands

Uninstalling Packages

$ sudo apt-get remove --purge oracle-java11-installer-local

Searching where are the Packages

$ whereis <package-name>

Command for Debugging

Searching file in a directory and subs using name

# find . -name <name of the file , can use wildcard > 

Search files for particular string

# grep -rnw . -e "<string>"

Networking Based commands

List all the interfaces with IP addresses

# ip -br -c addr show 

List all the interfaces with MAC addresses

# ip -br -c link show

Adding IP address to the interface

# ip addr add 10.0.0.2/24 dev eth0

Deleting IP address to the interface

ip addr del 10.0.0.2/24 dev eth0
     OR
# ifconfig <interface name> 0.0.0.0

Restarting an network interface

# ip link set eth1 up
# ip link set eth1 down

Deletion of VLAN / interface

# ip link delete <interface name> 

Changing the MAC address of an interface temporarily

sudo ifconfig <interface-name> down 
sudo ifconfig <interface-name> hw ether <new mac address>
sudo ifconfig <interface-name> up

Creating a vlan

sudo ip link add link enp2s0 name enp2s0.5 type vlan id 5
sudo ip addr add 192.168.1.121/24 dev enp2s0.5 
sudo ip link set enp2s0.5 up

Folder Operations Based Commands

Deleting a directory

rm -rf dir1

To know the files type in the directory

$ file *

To know the directory structure

tree <dir-name>

Routing Based Commands

Adding a multicasting address

# route add -net 224.0.0.0/4 dev enp2s0

Adding an gateway for particular network

# ip route add 192.168.10.0/24 via 192.168.5.1

Adding a default gateway

# route add default gw <ip> 

Accessing Remote PC

ssh access to a particular PC in the same network ( you need to know the password)

$ ssh <username>@<ip address> 

copying some file from this pc to another pc in same network

$ scp [user@]SRC_HOST_IP:]file1 [user@]DEST_HOST_IP:]file2

Copying some folder from current PC to another PC in same network

$ scp -r [user@]SRC_HOST_IP:]file1 [user@]DEST_HOST_IP:]file2

TC based General Commands

Knowing the status of QDISCS

$ tc  -s qdisc

Utilities

Installing the tomcat server

$ sudo apt install tomcat9 tomcat9-admin

Checking the status of tomcat server ( It should show 8080 )

$ ss -ltn

Disabling/Enabling tomcat

$ sudo systemctl enable tomcat9
$ sudo systemctl disable tomcat9

Installing default jdk

$ sudo add-apt-repository ppa:linuxuprising/java

Stopping the apache service

Windows: 
Search > Services > apache tomcat > stop 

Stopping the applications listening on given port

Windows: 
netstat -o -n -a | findstr 0.0:8080
TCP    0.0.0.0:3000      0.0.0.0:0              LISTENING       3116

taskkill /F /PID 3116

LINUX: 
lsof -i :8080
kill $(lsof -t -i :8080)

Ethtool Based Commands for NIC info

to know the Timestamping details regarding interface

ethtool -T <interface name> 

to know the statistics of the interface

ethtool -S <interface name> 

to know if the port contains HW queues

ethtool -l <interface_name>

to change the settings of queues in HW Queues.

ethtool -L <interface_name> tx <number_of_queues> 

Tar Based Commands

Extracting the tar.gz in specific directory

 tar -xvzf icon-j7200-icon-bam-dvw51.3-1-images_1.tar.gz -C ./navnit_extracted_images/

Netstat Commands

To know the ports open for TCP connection

netstat -anpl