making script compatible with zsh for absolutely no reason

macos-guest-virtualbox.sh

@@ -2,7 +2,7 @@
 # Push-button installer of macOS on VirtualBox
 # (c) myspaghetti, licensed under GPL2.0 or higher
 # url: https://github.com/myspaghetti/macos-guest-virtualbox
-# version 0.89.5
+# version 0.89.6
 
 # Dependencies: bash  coreutils  gzip  unzip  wget  xxd  dmg2img
 # Supported versions:
@@ -102,7 +102,8 @@ clear_input_buffer_then_read
 
 # check dependencies
 
-function check_bash_version() {
+function check_shell() {
+if [[ "${SHELL}" =~ /bash ]]; then
     if [[ -z "${BASH_VERSION}" ]]; then
         echo "Can't determine BASH_VERSION. Exiting."
         exit
@@ -117,6 +118,19 @@ elif [[ "${BASH_VERSION:0:1}" -eq 4 && "${BASH_VERSION:2:1}" -le 2 ]]; then
         echo "Please run this script on Bash 4.3 or higher."
         exit
     fi
+elif [[ "${SHELL}" =~ /zsh ]]; then
+    if [[ -z "${ZSH_VERSION}" ]]; then
+        echo "Can't determine ZSH_VERSION. Exiting."
+        exit
+    elif [[ "${ZSH_VERSION:0:1}" -lt 5 ]]; then
+        echo "Please run this script on zsh 5 or higher."
+        exit
+    fi
+    setopt extendedglob sh_word_split ksh_arrays posix_argzero
+else
+    echo "Can't determine SHELL. Exiting."
+    exit
+fi
 }
 
 function check_gnu_coreutils_prefix() {
@@ -176,7 +190,8 @@ if [[ -z "$(echo "xxd" | xxd -p 2>/dev/null)" || \
 fi
 
 # wget supports --show-progress from version 1.16
-if [[ "$(wget --version 2>/dev/null | head -n 1)" =~ 1\.1[6-9]|1\.2[0-9] ]]; then
+regex='1\.1[6-9]|1\.2[0-9]'
+if [[ "$(wget --version 2>/dev/null | head -n 1)" =~ ${regex} ]]; then
     wgetargs="--quiet --continue --show-progress"  # pretty
 else
     wgetargs="--continue"  # ugly
@@ -342,10 +357,9 @@ if [[ -n "$(VBoxManage showvminfo "${vm_name}" 2>/dev/null)" ]]; then
     echo ''
     echo 'A virtual machine named "'"${vm_name}"'" already exists.'
     printf "${warning_color}"'Delete existing virtual machine "'"${vm_name}"'"?'"${default_color}"
-    delete=""
+    prompt_delete_y_n
-    read -n 1 -p ' [y/N] ' delete
+    if [[ "${delete}" == "y" ]]; then
-    echo ""
+        echo "Deleting ${vm_name} virtual machine."
-    if [[ "${delete,,}" == "y" ]]; then
         VBoxManage unregistervm "${vm_name}" --delete
     else
         echo ""
@@ -653,10 +667,9 @@ print_dimly "stage: create_install_vdi"
 if [[ -w "Install ${macOS_release_name}.vdi" ]]; then
     echo '"'"Install ${macOS_release_name}.vdi"'" virtual disk image exists.'
     printf "${warning_color}"'Delete "'"Install ${macOS_release_name}.vdi"'"?'"${default_color}"
-    delete=""
+    prompt_delete_y_n
-    read -n 1 -p " [y/N] " delete
     echo ""
-    if [[ "${delete,,}" == "y" ]]; then
+    if [[ "${delete}" == "y" ]]; then
         if [[ "$( VBoxManage list runningvms )" =~ \""${vm_name}"\" ]];
         then
             echo '"'"Install ${macOS_release_name}.vdi"'" may be deleted'
@@ -753,6 +766,7 @@ fi
 echo "Starting virtual machine ${vm_name}. This should take a couple of minutes."
 ( VBoxManage startvm "${vm_name}" >/dev/null 2>&1 )
 echo "While the script is running, please do not interact with the virtual machine."
+[[ -z "${kscd}" ]] && declare_scancode_dict
 prompt_lang_utils
 prompt_terminal_ready
 print_dimly "Please wait"
@@ -839,6 +853,7 @@ if [[ -n $(
 fi
 echo "The VM will boot from the populated installer base system virtual disk."
 ( VBoxManage startvm "${vm_name}" >/dev/null 2>&1 )
+[[ -z "${kscd}" ]] && declare_scancode_dict
 prompt_lang_utils
 prompt_terminal_ready
 add_another_terminal
@@ -929,10 +944,8 @@ else
     fi
     echo ""
     printf "${warning_color}"'Delete temporary files?'"${default_color}"
-    delete=""
+    prompt_delete_y_n
-    read -n 1 -p " [y/N] " delete
+    if [[ "${delete}" == "y" ]]; then
-    echo ""
-    if [[ "${delete,,}" == "y" ]]; then
         rm "${macOS_release_name}_Apple"* \
            "${macOS_release_name}_BaseSystem"* \
            "${macOS_release_name}_Install"* \
@@ -969,17 +982,18 @@ patiently and, less than ten times, press enter when prompted.
 The script is divided into stages. Stage titles may be given as command-line
 arguments for the script. When the script is run with no command-line
 arguments, each of the available stages except \"${low_contrast_color}documentation${default_color}\" and
-\"${low_contrast_color}troubleshoot${default_color}\" is executed in succession in the order listed:
+\"${low_contrast_color}troubleshoot${default_color}\" is performed in succession in the order listed:
 
 ${low_contrast_stages}
-The stage \"${low_contrast_color}documentation${default_color}\" and \"${low_contrast_color}troubleshoot${default_color}\" is only executed when it is
+Either of the stages \"${low_contrast_color}documentation${default_color}\" and \"${low_contrast_color}troubleshoot${default_color}\" is only performed when
-specified as the first command-line argument, with all subsequent arguments
+it is specified as the first command-line argument, with all subsequent
-ignored. When specified after any argument, \"${low_contrast_color}documentation${default_color}\" and \"${low_contrast_color}troubleshoot${default_color}\"
+arguments ignored. When specified after any argument, either of \"${low_contrast_color}documentation${default_color}\"
-is ignored.
+and \"${low_contrast_color}troubleshoot${default_color}\" is ignored.
 
-The four stages \"${low_contrast_color}check_bash_version${default_color}\", \"${low_contrast_color}check_gnu_coreutils_prefix${default_color}\",
+The stage \"${low_contrast_color}check_shell${default_color}\" is always performed when the script loads.
-\"${low_contrast_color}set_variables${default_color}\", and \"${low_contrast_color}check_dependencies${default_color}\" are always performed when any stage
+The stages \"${low_contrast_color}check_gnu_coreutils_prefix${default_color}\", \"${low_contrast_color}set_variables${default_color}\", and
-title other than \"${low_contrast_color}documentation${default_color}\" or \"${low_contrast_color}troubleshoot${default_color}\" is specified as the first
+\"${low_contrast_color}check_dependencies${default_color}\" are always performed when any stage title other than
+\"${low_contrast_color}documentation${default_color}\" or \"${low_contrast_color}troubleshoot${default_color}\" is specified as the first
 argument, and the rest of the stages are parsed only after the checks pass.
 
         ${highlight_color}EXAMPLES${default_color}
@@ -1162,7 +1176,9 @@ function sleep() {
 # Virtualbox Mac scancodes found here:
 # https://wiki.osdev.org/PS/2_Keyboard#Scan_Code_Set_1
 # First half of hex code - press, second half - release, unless otherwise specified
-declare -A kscd=(
+function declare_scancode_dict() {
+    declare -gA kscd
+    kscd=(
         ["ESC"]="01 81"
         ["1"]="02 82"
         ["2"]="03 83"
@@ -1296,6 +1312,7 @@ declare -A kscd=(
         [">"]="2A 34 B4 AA"
         ["?"]="2A 35 B5 AA"
     )
+}
 
 function clear_input_buffer_then_read() {
     while read -d '' -r -t 0; do read -d '' -t 0.1 -n 10000; break; done
@@ -1304,8 +1321,9 @@ function clear_input_buffer_then_read() {
 
 # read variable kbstring and convert string to scancodes and send to guest vm
 function send_keys() {
-    scancode=$(for (( i=0; i < ${#kbstring}; i++ ));
+    scancode=$(for (( i=0; i < ${#kbstring}; i++ )); do
-               do c[i]=${kbstring:i:1}; echo -n ${kscd[${c[i]}]}" "; done)
+                 c[${i}]=${kbstring:${i}:1}; echo -n ${kscd[${c[${i}]}]}" "
+               done)
     VBoxManage controlvm "${vm_name}" keyboardputscancode ${scancode} 1>/dev/null 2>&1
 }
 
@@ -1373,9 +1391,21 @@ function would_you_like_to_know_less() {
     fi
 }
 
+function prompt_delete_y_n() {
+    delete=""
+    if [[ "${SHELL}" =~ /zsh ]]; then
+        read -s -q delete\?' [y/N] '
+        delete="${delete:l}"
+    elif [[ "${SHELL}" =~ /bash ]]; then
+        read -n 1 -p ' [y/N] ' delete
+        delete="${delete,,}"
+    fi
+    echo ""
+}
+
 # command-line argument processing
 stages='
-    check_bash_version 
+    check_shell
     check_gnu_coreutils_prefix
     set_variables
     welcome
@@ -1396,12 +1426,14 @@ stages='
     documentation
     troubleshoot
 '
+check_shell
 stages_without_newlines="${stages//[$'\r\n']/}"
 [[ "${1}" = "documentation" ]] && documentation && exit
 if [[ "${1}" = "troubleshoot" ]]; then set_variables; check_dependencies >/dev/null; troubleshoot; exit; fi
-stages="${stages//documentation/}"  # strip all occurrences of "documentation"
+stages_without_newlines="${stages//[$'\r\n']/ }"                      # replace newline with space character
-stages="${stages//troubleshoot/}"   # strip all occurrences of "troubleshoot"
+stages_without_newlines="${stages_without_newlines//documentation/}"  # strip all occurrences of "documentation"
-[[ -z "${1}" ]] && for stage in ${stages}; do ${stage}; done && exit
+stages_without_newlines="${stages_without_newlines//troubleshoot/}"   # strip all occurrences of "troubleshoot"
+[[ -z "${1}" ]] && for stage in ${stages_without_newlines}; do ${stage}; done && exit
 # every stage name must be preceded and followed by a space character
 # for the command-line argument checking below to work
 for argument in $@; do
@@ -1415,7 +1447,6 @@ for argument in $@; do
         exit
     fi
 done
-check_bash_version
 check_gnu_coreutils_prefix
 set_variables
 check_dependencies