useful Linux stuff

This is a collection of useful Linux commands and procedures that I compiled as a reference for me since I always forget this stuff. Hopefully it will prove to be useful for others too 🙂

 

 

Creating a bootable USB installation key

http://www.ubuntu.com/download/desktop/create-a-usb-stick-on-mac-osx

 

Resetting root password

http://linuxconfig.org/recover-a-forgotten-root-password-on-redhat-7-linux-selinux-system

It’s happened to me before, and this page was useful in quickly resetting the root password from the console.

  1. press ‘e’ at boot menu
  2. find and  replace ‘rhgb quiet’ with ‘init=/bin/bash’
  3. press ‘ctrl+x’
  4. # mount | grep root
  5. # mount -o remount,rw /
  6. # mount | grep root
  7. # passwd
  8. # touch /.autorelabel
  9. # exec /sbin/init

Networking

Hostname

hostnamectl status
hostnamectl set-hostname node.domain
hostnamectl set-hostname "pretty name" --pretty
hostnamectl set-chassis server
hostnamectl set-icon-name computer-server

 

Static IP

/etc/sysconfig/network-scripts/ifcfg-enp0s3

BOOTPROTO=static
IPADDR=x.x.x.x
NETMASK=255.255.255.0
GATEWAY=x.x.x.x
DNS1=8.8.8.8
DNS2=8.8.4.4
NM_CONTROLLED=no
...
PEERDNS=no
...
ONBOOT=yes

/etc/resolv.conf

nameserver 8.8.8.8
nameserver 8.8.4.4

restart the network interface with:

/etc/init.d/network restart

 

hosts file

/etc/hosts

255.255.255.255 name.domain alias

 

ssh without password

Generate keys and copy to hosts:

ssh-keygen
ssh-copy-id -i ~/.ssh/id_rsa.pub remote-host-name

On a Mac without ssh-copy-id, I used this command for copying keys:

cat ~/.ssh/id_rsa.pub | ssh user@remote-host-name 'umask 0077; mkdir -p .ssh; cat >> .ssh/authorized_keys && echo "Key copied"'

 

Installing Java

sudo yum install java-1.7.0-openjdk-devel

 

setting up a user with sudo

 

setting up NTP

yum install ntp ntpdate ntp-doc
chkconfig ntpd on
ntpdate pool.ntp.org
chkconfig ntpd on
service ntpd start

http://www.tecmint.com/install-ntp-server-in-centos/

 

Install openssl

yum upgrade openssl

rpm -qa | grep openssl

openssl-1.0.1e-16.el6.x86_64

 

 

disable firewalld

systemctl status firewalld

systemctl disable firewalld

 

 

install httpd

yum clean all

yum -y update

yum -y install httpd

systemctl enable httpd

systemctl start httpd

systemctl status httpd

 

apachectl start

apachectl stop

apachectl restart

apachectl status

 

disable SELinux

vi /etc/sysconfig/selinux

SELINUX=disabled

 

https://wiki.centos.org/HowTos/Https