====== Using Aliases in Raspbian ======
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Aliases are a way of assinging a complex command to an easy to remember word. Looking at the command below:
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        ip addr |grep '[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}'
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This returns just the IP part of the output from an //**ip addr**// command, making the output much easier to read, however remembering and typing the command requires more effort than it saves. For this then we can create an alias.
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I want an alias called **showip** that acutally does the same as typing ip addr |grep '[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}'
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You need to edit the .bash file for the logged in user who will use this alias. I am logged in as pi, so I will edit that bash file.\ 
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Navigate to pi home folder:
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     cd /home/pi
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Show the list of files:
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     ls -al to show file list, you will see a list of files, including one called .bashrc\\ 
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Edit the .bashrc file by entering:
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      sudo nano /home/pi/.bashrc
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My default .bashrc file looks like this:
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    # ~/.bashrc: executed by bash(1) for non-login shells.
    # see /usr/share/doc/bash/examples/startup-files (in the package bash-doc)
    # for examples
    
    # If not running interactively, don't do anything
    case $- in
        *i*) ;;
          *) return;;
    esac
    
    # don't put duplicate lines or lines starting with space in the history.
    # See bash(1) for more options
    HISTCONTROL=ignoreboth
    
    # append to the history file, don't overwrite it
    shopt -s histappend
    
    # for setting history length see HISTSIZE and HISTFILESIZE in bash(1)
    HISTSIZE=1000
    HISTFILESIZE=2000
    
    # check the window size after each command and, if necessary,
    # update the values of LINES and COLUMNS.
    shopt -s checkwinsize
    
    # If set, the pattern "**" used in a pathname expansion context will
    # match all files and zero or more directories and subdirectories.
    #shopt -s globstar
        
    # make less more friendly for non-text input files, see lesspipe(1)
    #[ -x /usr/bin/lesspipe ] && eval "$(SHELL=/bin/sh lesspipe)"
    
    # set variable identifying the chroot you work in (used in the prompt below)
    if [ -z "${debian_chroot:-}" ] && [ -r /etc/debian_chroot ]; then
        debian_chroot=$(cat /etc/debian_chroot)
    fi
    
    # set a fancy prompt (non-color, unless we know we "want" color)
    case "$TERM" in
        xterm-color) color_prompt=yes;;
    esac
    
    # uncomment for a colored prompt, if the terminal has the capability; turned
    # off by default to not distract the user: the focus in a terminal window
    # should be on the output of commands, not on the prompt
    force_color_prompt=yes
    
    if [ -n "$force_color_prompt" ]; then
        if [ -x /usr/bin/tput ] && tput setaf 1 >&/dev/null; then
            # We have color support; assume it's compliant with Ecma-48
            # (ISO/IEC-6429). (Lack of such support is extremely rare, and such
            # a case would tend to support setf rather than setaf.)
            color_prompt=yes
        else
            color_prompt=
        fi
    fi
    
    if [ "$color_prompt" = yes ]; then
        PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w \$\[\033[00m\] '
    else
        PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '
    fi
    unset color_prompt force_color_prompt
    
    # If this is an xterm set the title to user@host:dir
    case "$TERM" in
    xterm*|rxvt*)
        PS1="\[\e]0;${debian_chroot:+($debian_chroot)}\u@\h: \w\a\]$PS1"
        ;;
    *)
        ;;
    esac
    
    # enable color support of ls and also add handy aliases
    if [ -x /usr/bin/dircolors ]; then
        test -r ~/.dircolors && eval "$(dircolors -b ~/.dircolors)" || eval "$(dircolors -b)"
        alias ls='ls --color=auto'
        #alias dir='dir --color=auto'
        #alias vdir='vdir --color=auto'
    
        alias grep='grep --color=auto'
        alias fgrep='fgrep --color=auto'
        alias egrep='egrep --color=auto'
    fi
    
    # colored GCC warnings and errors
    #export GCC_COLORS='error=01;31:warning=01;35:note=01;36:caret=01;32:locus=01:quote=01'
    
    # some more ls aliases
    #alias ll='ls -l'
    #alias la='ls -A'
    #alias l='ls -CF'
    
    # Alias definitions.
    # You may want to put all your additions into a separate file like
    # ~/.bash_aliases, instead of adding them here directly.
    # See /usr/share/doc/bash-doc/examples in the bash-doc package.
    
    if [ -f ~/.bash_aliases ]; then
        . ~/.bash_aliases
    fi
    
    # enable programmable completion features (you don't need to enable
    # this, if it's already enabled in /etc/bash.bashrc and /etc/profile
    # sources /etc/bash.bashrc).
    if ! shopt -oq posix; then
      if [ -f /usr/share/bash-completion/bash_completion ]; then
        . /usr/share/bash-completion/bash_completion
      elif [ -f /etc/bash_completion ]; then
        . /etc/bash_completion
      fi
    fi
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Now add the new alias:
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        alias showip=" ip addr |grep '[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}'"
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save the file and exit:
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        ctrl-x - yes - enter
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You have to restart the bash for any new aliases to work
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        . .bashrc
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If you want to see if the alias is now listed, from the command prompt just type:
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        alias
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You should now be able to type your new command at the command line and get an output:
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        showip
            inet 127.0.0.1/8 scope host lo
            inet 192.168.27.30/24 brd 192.168.27.255 scope global eth0
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