[[!toc levels=99]]

## Package management

https://help.ubuntu.com/community/AptGet/Howto

[Ubuntu comparison of apt-get vs. yum commands](https://help.ubuntu.com/community/SwitchingToUbuntu/FromLinux/RedHatEnterpriseLinuxAndFedora)

    # show installed packages
    dpkg --list

    # show info for a package
    dpkg --status package_name

    # show files owned by a package
    dpkg --listfiles package_name

    # resynchronize the package index files from their sources
    apt-get update

    # install the newest versions installed packages
    apt-get upgrade

    # install packages that are "kept back"
    apt-get dist-upgrade

    # for clearing out unused linux-headers, for example
    apt-get autoremove

    # search for packages with a given string (i.e. json)
    apt-cache search json

### `apt-get dist-upgrade`

"-y  Assume Yes to all queries and do not prompt" is not recommended for `apt-get dist-upgrade`

http://askubuntu.com/questions/601/the-following-packages-have-been-kept-back-why-and-how-do-i-solve-it

http://askubuntu.com/questions/81585/what-is-dist-upgrade-and-why-does-it-upgrade-more-than-upgrade

## User management

    useradd -m myuser -s /bin/bash

https://help.ubuntu.com/community/AddUsersHowto

## Shutdown and restart

    poweroff

    reboot

## Change default $EDITOR from nano to vim

    update-alternatives --config editor

Choose "vim.basic".

## Give user sudo access

    newuser    ALL=(ALL:ALL) ALL

or

    newuser    ALL=NOPASSWD: ALL

https://www.digitalocean.com/community/tutorials/how-to-add-delete-and-grant-sudo-privileges-to-users-on-a-debian-vps

## iptables

    # so that firewall rules load at boot
    apt-get install iptables-persistent
    # edit rules
    vim /etc/iptables/rules.v4 
    # reload rules
    iptables-restore < /etc/iptables/rules.v4
    # save rules
    invoke-rc.d iptables-persistent save

### Sample iptables firewall rules

    root@server2:~# cat /etc/iptables/rules.v4
    # Generated by iptables-save v1.4.21 on Wed Oct 14 22:17:08 2015
    *filter
    :INPUT ACCEPT [0:0]
    :FORWARD ACCEPT [0:0]
    :OUTPUT ACCEPT [72:34181]
    -A INPUT -i lo -j ACCEPT
    -A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
    -A INPUT -p tcp -m tcp --dport 22 -j ACCEPT
    -A INPUT -p tcp -m tcp --dport 80 -j ACCEPT
    -A INPUT -j DROP
    COMMIT
    # Completed on Wed Oct 14 22:17:08 2015
    root@server2:~#

https://help.ubuntu.com/community/IptablesHowTo

https://www.digitalocean.com/community/tutorials/how-to-set-up-a-firewall-using-iptables-on-ubuntu-14-04

## Apache httpd

    sudo apt-get install apache2

https://www.digitalocean.com/community/tutorials/how-to-set-up-apache-virtual-hosts-on-ubuntu-14-04-lts

## MySQL

    sudo apt-get install mysql-server

https://www.digitalocean.com/community/tutorials/a-basic-mysql-tutorial