Advanced Bash−Scripting Guide

Advanced Bash−Scripting Guide
echo "var1 = $var1"
# var1 = first line second line
# For each line terminated by a "\",
# you get a prompt on the next line to continue feeding characters into var1.
echo; echo
echo "Enter another string terminated by a \\ , then press ."
read −r var2 # The −r option causes the "\" to be read literally.
# first line \
echo "var2 = $var2"
# var2 = first line \
# Data entry terminates with the first .
echo
exit 0
The read command has some interesting options that permit echoing a prompt and even reading
keystrokes without hitting ENTER.
# Read a keypress without hitting ENTER.
read −s −n1 −p "Hit a key " keypress
echo; echo "Keypress was "\"$keypress\""."
# −s option means do not echo input.
# −n N option means accept only N characters of input.
# −p option means echo the following prompt before reading input.
# Using these options is tricky, since they need to be in the correct order.
The −n option to read also allows detection of the arrow keys and certain of the other unusual keys.
Example 11−5. Detecting the arrow keys
#!/bin/bash
# arrow−detect.sh: Detects the arrow keys, and a few more.
# Thank you, Sandro Magi, for showing me how.
# −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
# Character codes generated by the keypresses.
arrowup='\[A'
arrowdown='\[B'
arrowrt='\[C'
arrowleft='\[D'
insert='\[2'
delete='\[3'
# −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
SUCCESS=0
OTHER=65
echo −n "Press a key... "
Chapter 11. Internal Commands and Builtins 128