First of all, we use the source command to include the TwitterOAuth.sh library, so we can use its functions to access Twitter. The TO_init function initializes the library.

Every app needs to get an OAuth token and token secret the first time it is used. If these are not present, we use the TO_access_token_helper library function to acquire them. Once we have the tokens, we save them to a config file so we can simply source it the next time the script is run.

The TO_statuses_home_timeline library function fetches the tweets from Twitter. This data is retuned as a single long string in JSON format, which starts like this:

[{"created_at":"Thu Nov 10 14:45:20 +0000    
"016","id":7...9,"id_str":"7...9","text":"Dining...

Each tweet starts with the "created_at" tag and includes a text and a screen_name tag. The script will extract the text and screen name data and display only those fields.

The script assigns the long string to the TO_ret variable.

The JSON format uses quoted strings for the key and may or may not quote the value. The key/value pairs are separated by commas, and the key and value are separated by a colon (:).

The first sed replaces each " character set with a newline, making each key/value a separate line. These lines are piped to another sed command to replace each occurrence of ": with a tilde (~), which creates a line like this:

screen_name~"Clif_Flynt" 

The final awk script reads each line. The -F~ option splits the line into fields at the tilde, so $1 is the key and $2 is the value. The if command checks for text or screen_name. The text is first in the tweet, but it's easier to read if we report the sender first; so the script saves a text return until it sees a screen_name, then prints the current value of $2 and the saved value of the text.

The TO_statuses_update library function generates a tweet. The empty first parameter defines our message as being in the default format, and the message is a part of the second parameter.