Tidy the script startup code

macos-guest-virtualbox.sh

@@ -1096,17 +1096,25 @@ fi
 function and_all_subsequent_stages() {
     # if exactly two arguments were specified on the command line, and the first is a stage title,
     # then perform all stages subsequent to the specified stage, otherwise do nothing.
-    # first_argument is already sanitized so it's safe (though incorrect) to use as a regex (for brevity)
-    first_argument=${specified_arguments%% *}
-    last_argument=${specified_arguments##* }
-    [[ "${first_argument} ${last_argument}" = "${specified_arguments}" ]] && \
-    [[ "${stages}" =~ "${first_argument}" ]] && \
-    for stage in ${stages##*${first_argument}}; do ${stage}; done
+    if [[ ${#specified_arguments[@]} == 2 ]]; then
+        local stage
+        local first_argument=${specified_arguments[0]}
+        local run=n
+
+        for stage in "${stages[@]}"; do
+            [[ $run == n ]] || "$stage"
+
+            if [[ $stage == "$first_argument" ]]; then
+                # Run all subsequent stages.
+                run=y
+            fi
+        done
+    fi
 }
 
 function documentation() {
 low_contrast_stages=""
-for stage in ${stages}; do
+for stage in "${stages[@]}"; do
     low_contrast_stages="${low_contrast_stages}"'    '"${low_contrast_color}${stage}${default_color}"$'\n'
 done
 echo -ne "\n        ${highlight_color}NAME${default_color}
@@ -1685,7 +1693,7 @@ function prompt_delete_y_n() {
 
 # command-line argument processing
 check_shell
-stages='
+stages=(
     check_gnu_coreutils_prefix
     set_variables
     welcome
@@ -1703,27 +1711,58 @@ stages='
     create_target_virtual_disk
     populate_macos_target_disk
     prompt_delete_temporary_files
-'
-[[ -z "${1}" ]] && for stage in ${stages}; do ${stage}; done && exit
-[[ "${1}" = "documentation" ]] && documentation && exit
-valid_arguments=(${stages//$'[\r\n]'/ } check_shell troubleshoot documentation and_all_subsequent_stages)
-specified_arguments="$@"  # this variable is used in the function "and_all_subsequent_stages"
-for specified_arg in "$@"; do
-    there_is_a_match=""
-    # doing matching the long way to prevent delimiter confusion
-    for valid_arg in "${valid_arguments[@]}"; do
-        [[ "${valid_arg}" = "${specified_arg}" ]] && there_is_a_match="true" && break
+)
+
+if [[ $# == 0 ]]; then
+    for stage in "${stages[@]}"; do
+        "$stage"
     done
-    if [[ -z "${there_is_a_match}" ]]; then
-        echo -e "\nOne or more specified arguments is not recognized."
-        echo -e "\nRecognized stages:\n${stages}"
-        echo -e "Other recognized arguments:\n\n    check_shell\n    documentation\n    troubleshoot\n    and_all_subsequent_stages"
-        echo -e "\nView documentation by entering the following command:"
-        would_you_like_to_know_less
+
+    exit
+fi
+
+if [[ $1 == documentation ]]; then
+    documentation
+    exit
+fi
+
+other_commands=(
+    check_shell
+    troubleshoot
+    documentation
+    and_all_subsequent_stages
+)
+
+specified_arguments=("$@") # this variable is used in the function "and_all_subsequent_stages"
+for specified_arg; do
+    there_is_a_match=n
+    for valid_arg in "${stages[@]}" "${other_commands[@]}"; do
+        if [[ $valid_arg == "$specified_arg" ]]; then
+            there_is_a_match=y
+            break
+        fi
+    done
+
+    if [[ $there_is_a_match == n ]]; then
+        cat <<EOF
+
+One or more specified arguments is not recognized.
+
+Recognized stages:
+$(printf '    %s\n' "${stages[@]}")
+
+Other recognized arguments:
+$(printf '    %s\n' "${other_commands[@]}")
+
+View documentation by entering the following command:
+$(would_you_like_to_know_less)
+
+EOF
         exit
     fi
 done
+
 check_gnu_coreutils_prefix
 set_variables
 check_dependencies
-for argument in "$@"; do ${argument}; done
+for argument; do "${argument}"; done