Mac OS X Leopard - ARCAism

The first thing you may notice is that unlike the echo command, printf does not automatically
add a linefeed to each statement. By using printf in line 3, the prompt for the read
statement appears on the some line rather than the line below.
The read statement is on line 4, and it’s fairly easy: the read command followed by a variable
to contain our input (cleverly called input).
In line 5 we set the input as our primary script arguments.
Line 6 starts a counter and starts it with $#, which is a special variable that tells the total
number of arguments assigned by set in line 5.
Line 7 provides some text for our output.
Line 8 begins a for loop that will iterate through each of the arguments set in line 5. The $@
is another one of those special variables that contains all of our arguments in a single variable. In
this case, $@ and $input will contain the same values.
Line 9 starts the for loop.
Line 10 decreases the value of our counter by 1.
Line 11 uses an if statement to see whether our counter is greater than 0. The counter is set
up so that when it hits 0, the loop will be on our final input argument, so we continue the loop
on line 13 until we reach the last of our inputs and then switch over to line 15.
Line 13 uses the printf statement to print one of our arguments surrounded by quotes. To
get the quote to print, rather than get interpreted as the closing or opening of the text we are
printing, we need to escape the ". We do this by preceding the quote symbol with a backslash (\)
. printf knows a number of these formatting escape characters (which are actually borrowed
from the C programming language) and will automatically expand them into their proper form
when printing. Table 19-3 lists the common escape characters.
Table 19-3. Escape Character Expansion
Escape Character Name Output Result
\a Alert (bell) Activates the terminals bell. Depending on your Terminal
preferences (set on the Advanced tab of the Terminal
Inspector), this will either flash the terminal screen or make
an audible noise (or both or neither). By default the terminal
window will flash.
\b Backspace Moves the cursor back one space.
\f Form feed Clears the screen. Traditionally this would eject the current
sheet of paper and start a new sheet.
\n Newline Moves the input to the beginning of the next line, like hitting
Return.
\r Carriage return Moves the cursor back to the beginning of the current line;
any further input would overwrite what’s already there.
\t Tab Moves the cursor one tab space to the right.
\v Vertical tab Moves the cursor down one line; however, unlike \n, it will
not return to the beginning of the line.
\\ Backslash Prints the backslash character.
\' Single quote Prints a single quote character.
\" Double quote Prints a double quote character.
CHAPTER 19 EXTENDING THE POWER OF DARWIN 337