Created
March 14, 2016 03:34
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Bash: General-purpose Yes/No prompt function ("ask")
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# This is a general-purpose function to ask Yes/No questions in Bash, either | |
# with or without a default answer. It keeps repeating the question until it | |
# gets a valid answer. | |
ask() { | |
# http://djm.me/ask | |
while true; do | |
if [ "${2:-}" = "Y" ]; then | |
prompt="Y/n" | |
default=Y | |
elif [ "${2:-}" = "N" ]; then | |
prompt="y/N" | |
default=N | |
else | |
prompt="y/n" | |
default= | |
fi | |
# Ask the question - use /dev/tty in case stdin is redirected from somewhere else | |
read -p "$1 [$prompt] " REPLY </dev/tty | |
# Default? | |
if [ -z "$REPLY" ]; then | |
REPLY=$default | |
fi | |
# Check if the reply is valid | |
case "$REPLY" in | |
Y*|y*) return 0 ;; | |
N*|n*) return 1 ;; | |
esac | |
done | |
} | |
# EXAMPLE USAGE: | |
if ask "Do you want to do such-and-such?"; then | |
echo "Yes" | |
else | |
echo "No" | |
fi | |
# Default to Yes if the user presses enter without giving an answer: | |
if ask "Do you want to do such-and-such?" Y; then | |
echo "Yes" | |
else | |
echo "No" | |
fi | |
# Default to No if the user presses enter without giving an answer: | |
if ask "Do you want to do such-and-such?" N; then | |
echo "Yes" | |
else | |
echo "No" | |
fi | |
# Only do something if you say Yes | |
if ask "Do you want to do such-and-such?"; then | |
said_yes | |
fi | |
# Only do something if you say No | |
if ! ask "Do you want to do such-and-such?"; then | |
said_no | |
fi | |
# Or if you prefer the shorter version: | |
ask "Do you want to do such-and-such?" && said_yes | |
ask "Do you want to do such-and-such?" || said_no |
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