venkatmarepalli · February 28, 2019 18:41
diff --git a/Useful_Shell_Commands.sh b/Useful_Shell_Commands.sh
 #How to determine the current shell I'm working on?
 #Ref: https://stackoverflow.com/questions/3327013/how-to-determine-the-current-shell-im-working-on
 echo $SHELL
 echo $0
 ps  -ef | grep $$ | grep -v grep

 #Find Linux Kernel version
 uname -a

 #Find Linux Version info
 cat /proc/version

 #Distribution version
 cat /etc/*release

 #Command to display chmod permissions of a file
 stat -c '%a %n' *
 stat -c '%a %n' filename

 #Disk usage
 du -xk | sort -n | tail -25
 #Summarize and display current directory disk usage in human readable format ex: 10K, 11M etc
 du -sh

 #Copying files from local to ssh
 scp filenameFromCurrDir username@machinename:/home/user/folder

 #Getting files from remote machine to current machine. Executing scp in reverse way
 scp username@remoteMachineName:/file/to/send /where/to/put

 # Copying files from EC2 instance into the current directory (.)
 scp -i ~/.ssh/pemfile ec2-user@ip-address:/path/of/the/file/to/copy .

 #Taring
 tar -cvf myfile_20030617.tar folderinCurrentDir/* 

 #UnTaring
 tar -xf abc.tar

 #list of ports running
 netstat -lntu

 #list of ports running with service name
 netstat -tlnp

 #Translate Domain name into IP Address
 host www.google.com
 nslookup www.google.com

 #List all packages installed on the system, This is ony for Ubuntu or any Debian-based systems
 #Src: https://help.ubuntu.com/lts/serverguide/dpkg.html
 dpkg -l
 dpkg -l | grep apache2
 #List the files installed by package
 dpkg -L package_name

 #Checking size of the file or directory
 # Ref: https://stackoverflow.com/questions/11720079/how-can-i-see-the-size-of-files-and-directories-in-linux
 ls -l filename # Size of the file
 ls -l *        # Size of All the files in the current directory */
 ls -al *       # Size of All the files including hidden files in the current directory */
 ls -al dir/    # Size of All the files including hidden files in the 'dir' directory */

 #Gives you the summarized(-s) size of the directory in human readable(-h) format*/
 du -sh directory_name    
 #Gives you the apparent(-b) summarized(-s) size of all the files and directories in the current directory in human readable(-h) format*/
 du -bsh *                

 #Test if scripts in cron.hourly or cron.monthly are working or not
 #If by running this command it shows your file it means it worked. Otherwise, if doesn't show anything your file name is not valid.
 #The files in cron.hourly or cron.monthly should not have any extension ex: Rename script.sh to script by removing the extension
 run-parts --test /etc/cron.hourly

 #While running previously executed commands one can use !52 to execute 52nd command
 #To see the full previous command type first few characters and press Esc+P
 #To see a part phrase ex: cp a/b/c/ d/e/f when you type a/b and Esc+/ you will see /a/b/c/


 #How to Check if Your Linux System Is 32-bit or 64-bit
 lscpu
 #If cpu op-modes displays both 32 bit and 64 bit then it is 64 bit os running on the machine
 #Ref:https://www.howtogeek.com/198615/how-to-check-if-your-linux-system-is-32-bit-or-64-bit/

 #To create a 30GB random “dockerfile”, do this:
 dd if=/dev/urandom of=dockerfile bs=30GB count=1

 #To allow any display to be displayed on your machine when connecting using ssh and setting DISPLAY variable this setting helps. (One doesnt have to ssh with X option)
 xhost +


 #https://stackoverflow.com/questions/6377009/adding-public-key-to-ssh-authorized-keys-does-not-log-me-in-automatically
 #You need to verify the permissions of the authorized_keys file and the folder / parent folders in which it is located.
 #just generate a ssh key like:
 ssh-keygen -t rsa -C "your_email@youremail.com"
 #copy the content of ~/.ssh/id_rsa.pub and lastly add it to the remote machines ~/.ssh/authorized_keys
 scp -r ~/.ssh user@remotemachine:./
 cp ~/.ssh/id_rsa.pub ~/.ssh/authorized_keys

 chmod 700 ~/.ssh
 chmod 600 ~/.ssh/authorized_keys
 #You may also need to change/verify the permissions of your home directory to remove write access for the group and others.
 chmod go-w ~

 #Split file into multiple parts -d for numeric
 split -d -b 18350k nginx_error_psgi.log nginx_error_

 #Concatenate primary and intermediate certs for installing it on nginx server
 cat your_domain_name.crt intermediate.crt >> bundle.crt
	#How to determine the current shell I'm working on?
	#Ref: https://stackoverflow.com/questions/3327013/how-to-determine-the-current-shell-im-working-on
	echo $SHELL
	echo $0
	ps -ef \| grep $$ \| grep -v grep

	#Find Linux Kernel version
	uname -a

	#Find Linux Version info
	cat /proc/version

	#Distribution version
	cat /etc/*release

	#Command to display chmod permissions of a file
	stat -c '%a %n' *
	stat -c '%a %n' filename

	#Disk usage
	du -xk \| sort -n \| tail -25
	#Summarize and display current directory disk usage in human readable format ex: 10K, 11M etc
	du -sh

	#Copying files from local to ssh
	scp filenameFromCurrDir username@machinename:/home/user/folder

	#Getting files from remote machine to current machine. Executing scp in reverse way
	scp username@remoteMachineName:/file/to/send /where/to/put

	# Copying files from EC2 instance into the current directory (.)
	scp -i ~/.ssh/pemfile ec2-user@ip-address:/path/of/the/file/to/copy .

	#Taring
	tar -cvf myfile_20030617.tar folderinCurrentDir/*

	#UnTaring
	tar -xf abc.tar

	#list of ports running
	netstat -lntu

	#list of ports running with service name
	netstat -tlnp

	#Translate Domain name into IP Address
	host www.google.com
	nslookup www.google.com

	#List all packages installed on the system, This is ony for Ubuntu or any Debian-based systems
	#Src: https://help.ubuntu.com/lts/serverguide/dpkg.html
	dpkg -l
	dpkg -l \| grep apache2
	#List the files installed by package
	dpkg -L package_name

	#Checking size of the file or directory
	# Ref: https://stackoverflow.com/questions/11720079/how-can-i-see-the-size-of-files-and-directories-in-linux
	ls -l filename # Size of the file
	ls -l * # Size of All the files in the current directory */
	ls -al * # Size of All the files including hidden files in the current directory */
	ls -al dir/ # Size of All the files including hidden files in the 'dir' directory */

	#Gives you the summarized(-s) size of the directory in human readable(-h) format*/
	du -sh directory_name
	#Gives you the apparent(-b) summarized(-s) size of all the files and directories in the current directory in human readable(-h) format*/
	du -bsh *

	#Test if scripts in cron.hourly or cron.monthly are working or not
	#If by running this command it shows your file it means it worked. Otherwise, if doesn't show anything your file name is not valid.
	#The files in cron.hourly or cron.monthly should not have any extension ex: Rename script.sh to script by removing the extension
	run-parts --test /etc/cron.hourly

	#While running previously executed commands one can use !52 to execute 52nd command
	#To see the full previous command type first few characters and press Esc+P
	#To see a part phrase ex: cp a/b/c/ d/e/f when you type a/b and Esc+/ you will see /a/b/c/


	#How to Check if Your Linux System Is 32-bit or 64-bit
	lscpu
	#If cpu op-modes displays both 32 bit and 64 bit then it is 64 bit os running on the machine
	#Ref:https://www.howtogeek.com/198615/how-to-check-if-your-linux-system-is-32-bit-or-64-bit/

	#To create a 30GB random “dockerfile”, do this:
	dd if=/dev/urandom of=dockerfile bs=30GB count=1

	#To allow any display to be displayed on your machine when connecting using ssh and setting DISPLAY variable this setting helps. (One doesnt have to ssh with X option)
	xhost +


	#https://stackoverflow.com/questions/6377009/adding-public-key-to-ssh-authorized-keys-does-not-log-me-in-automatically
	#You need to verify the permissions of the authorized_keys file and the folder / parent folders in which it is located.
	#just generate a ssh key like:
	ssh-keygen -t rsa -C "your_email@youremail.com"
	#copy the content of ~/.ssh/id_rsa.pub and lastly add it to the remote machines ~/.ssh/authorized_keys
	scp -r ~/.ssh user@remotemachine:./
	cp ~/.ssh/id_rsa.pub ~/.ssh/authorized_keys

	chmod 700 ~/.ssh
	chmod 600 ~/.ssh/authorized_keys
	#You may also need to change/verify the permissions of your home directory to remove write access for the group and others.
	chmod go-w ~

	#Split file into multiple parts -d for numeric
	split -d -b 18350k nginx_error_psgi.log nginx_error_

	#Concatenate primary and intermediate certs for installing it on nginx server
	cat your_domain_name.crt intermediate.crt >> bundle.crt
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