Gyumeijie

Assumme that we have already installed babel-cli command using `npm install --global babel-cli`.

1. Configuration .babelrc, the basic format of this file is shown as the following:

{
  "presets": [],
  "plugins": []
}

2. Install some plunins

Gyumeijie

In most case, if a command takes a file name as a command line arg, we can also use the content of
the file as the standard input of a command, the two ways have the same effect.

For example, a directory contains the following files:

        example1.txt
        example2.txt
        example3.txt
        example4.txt
        example5.txt

Gyumeijie

# We first get a list of file with suffix 
# and then use `cut` utility to split the 
# full filename into a name and suffix using
# dot as delimiter.
cut -f1 -d'.' <<<$(ls *.*)

Gyumeijie

FILE SPACING:

 # double space a file
 sed G

 # double space a file which already has blank lines in it. Output file
 # should contain no more than one blank line between lines of text.
 sed '/^$/d;G'