Linux Commands

  • To find out what OS you're running

cat /etc/

  • To find out hardware specs:
RAM and CPU info:

cat /proc/meminfo

cat /proc/cpuinfo

Hard drive info:

df -H

  • Add user

sudo adduser username
sudo passwd username

  • Change an existing user to a sudo user
    sudo usermod -a -G sudo username

  • Delete user:

deluser jondoe

  • To add new user and include him in a particular group, e.g. groupname:

useradd username -g groupname

  • or to create user user81 and create his home directory in /home:

useradd -d /home/user81 user81

  • to create home directory for an existing user:

sudo mkdir /home/user1
sudo chown -R user1 /home/user1

  • To find out what groups user belongs to :

groups username

  • To add user userid to groupd groupname:

usermod -G groupname userid

  • find file with certain name - for example variables.none.tmpl, in certain directory tree - for example /var/www, (it will search through all the subdirectories as well) use:

sudo find /var/www -name 'variables.none.tmpl'

  • To find all files that contain text ear: (this will look through all files in tmp/container/ directory and all its subdirectories)

fgrep -r 'ear' tmp/container/*

  • To list all software packages installed on the current machine:
rpm -qa | less
  • To find the full name of the package:
rpm -qa | grep packageName
rpm -qa | grep mysql
  • To move all files in current directory to directory named destination:

mv * home/andrey/destination/

  • To compress into .tar.gz use the following syntax:

tar -zcvf archive_name.tar.gz directory_to_compress

  • To extract file filename.tar.gz:

tar xvzf filename.tar.gz

  • In order to copy files from this server to remote server to directory /home/akashliev/ (say, remote server has ip address

scp index.html akashliev@

  • To copy directory build run:

scp -r build/ akashliev@

  • To list all partitions of the hard drive:

sudo fdisk -l

  • To swapon partition (e.g. if partition name is /dev/sda3):

sudo swapon /dev/sda3

  • To install .deb package in ubuntu

sudo dpkg -i package.deb

  • To clear terminal ¬†fully (without the possibility to scroll up after it as it is the case with 'clear' command):