How to prompt for input in a Linux shell script

The simplest and most widely available method to get user input at a shell prompt is the ‘read‘ command. The best way to illustrate its use is a simple demonstration:
while true; do
-p "Do you wish to install this program?" yn
case $yn in
[Yy]* ) make install; break;;
[Nn]* ) exit;;
* ) echo "Please answer yes or no.";;
Another method, pointed out by Steven Huwig, is bash’s ‘select‘ command. Here is the same example using select:
echo "Do you wish to install this program?"
select yn in "Yes" "No"; do
case $yn in
Yes ) make install; break;;
No ) exit;;
With select you don’t need to sanitize the input… it prompts you with your choices, and you type a number corresponding to the choice you want. Select also loops automatically… there’s no need for a ‘while true’ loop to retry if they give invalid input.

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