Generic bash snippets

functions.sh

# Asserts that the script was invoked with valid arguments
assert_usage(){
    if [ $# -ne 1 ]; then
        echoerr "Usage: $0 (start | start | develop)"
        exit 1
    fi

}

# Begin actual script:
assert_usage $@

# do something based on first param
case "$1" in
    install) install;;
    clean) clean;;
    *) install;;
esac


# Prompts a given yes/no question. 
# Returns 0 if user answers yes, 1 if no
# Reprompts if different answer
ask_yes_no(){
    question=$1
    while true; do
        read -e -p "$question" -i "Y" yn
        case $yn in
             [Yy]* ) return 0;;
             [Nn]* ) return 1;;
        esac 
    done
}  
 
if ask_yes_no "Backup directory '$dest' already exists. Overwrite? [Y/n]";                       
then
	# do stuff
fi


# TODO(jroovers): modify this to pass array along (now it comes from the global scope)
ask_question_options(){
    question=$1
    PS3=$1 # PS3 is used by the select command to show question below the options
    select opt in "${options[@]}"
    do
        if array_contains "$opt" "${options[@]}"; then
           echo $opt
           return;
        fi
    done
}  

options=("stable/havana" "stable/icehouse" "master")
branch=$(ask_question_options "Select a devstack branch: ")
echo "Chosen branch: $branch"
exit 1