Tag: terminal

Below are some useful commands for those either just learning Ubuntu 14.04 or a resource for various commands. I will continually expand on them.

Directory Exists:

if [ ! -d "##DIRECTORY##" ]; then
fi

Format a Number as two digits even if it is 1:

$(printf %02d $variable)

Increment a Number:

variable=`expr $variable + 1`

Create a new file:

touch ##FILENAME##

Check if a file contains a string:

This will return 0 if it is not found.

$(echo `grep -c '##TextToSearch##' ##FileNameToSearch##`)

Create a link to a file:

ln -s ##OriginalFile## ##LinkedFile##

List all packages installed:

dpkg -l

Remove installed package:

sudo apt-get --purge remove ##PACKAGENAME##

Install Package:

sudo apt-get install ##PACKAGENAME##

Package Exists:

This will return 0 if it is not found.

$(echo `dpkg-query -l | grep -c ##PACKAGE_NAME##`)

Python Package Exists:

This will return 0 if it is not found.

$(echo `pip freeze | grep -c ##PACKAGE_NAME##`)

Get IP Address:

ip addr show

Find a file:

find / -type f -name "##FILENAME##"

Restart Service:

/etc/init.d/postgresql restart
invoke-rc.d postgresql restart

Kill a process:

kill ##PID##

Terminal Loop:

In the terminal let’s say you want to loop and display a value. You can do it like below. I am just printing free memory. But really you can do anything.

while true; do free -m | grep /+ | gawk '{ print $4 }'; sleep 2; done

Switch to root:

sudo su root

Add Text to File:

echo "##TextToAdd##" >> ##FileNameToAddTo##

Add Text Above Other Text:

sed -i 's/^##LookForText##/##TextToAdd##\n&/' ##FileNameToAddTo##

Loop:

until [ $Variable -gt 3 ]
do
done