Aliases

Use aliasing mechanism to assign a sequence of commands to a name.

Properties

  Something like a local variable only executable.

  Aliases run in current shell.

  Should be quoted when assigned to name. Like variable.

  Not exportable.

  But can be defined in .bashrc 

  Alias definition must fit on one line (can be long).
   Or use \ at end of line.

  Can use &&, ||, ;, & to put multiple commands in alias.

  Can use some scripting code if fit on a single line.
    alias t='for fn in *;do echo $fn; wc $fn;done'
    #Note single quotes to prevent $fn from being evaluated too soon.

  Technically, bash alias cannot take command line arguments.

  But arguments following an alias stay in place on the command line.
    Thus becoming part of the last command in alias.

  An alias can call another alias.
    But not itself.

  Redefinable by simply assigning a new sequence of commands. 

  
* C-shell version of alias can use history to take arguments, 
   but also did not have a function mechanism.

  Bash does have functions. Use these for more complex definitions.


Creation, listing, removal.

Creating

  alias  alias_name="command sequence"

Listing existing aliases.

  alias

  alias target_alias

Deleting
 
  unalias target_alias


Exporting

Because an alias is NOT exportable,
  1. Place your alias definition in .bashrc in your $HOME directory.

  2. Invoke .bashrc from .bash_profile in your $HOME directory.


Getting inteactive input from user

Although the bash alias cannot use the history mechanism to get
  arguments from the command line.

It can use the shell built-in  read  function to read input directly
  from the user.

The following alias prompts the user for two filenames and then swaps their
 contents.

alias swapper='read -p "1st file : " fn1; e read -p "2nd file : " fn2; mv $fn1 ${fn1}.tmp; mv $fn2 $fn1; mv ${fn1}.tmp $fn2'

Note the following :

This is a rather long alias, so it is best to edit it in a file and
then source the file. Be careful, there are no line breaks in this.

Because there are variable references in the alias, the whole alias is 
single quoted to prevent evaluation of variables during alias assignment.