diff --git a/bin/generate_readme.sh b/bin/generate_readme.sh
index d02052a..ac4d34f 100755
--- a/bin/generate_readme.sh
+++ b/bin/generate_readme.sh
@@ -1,13 +1,111 @@
 #!/usr/bin/env bash
-README="README.md"
 
-_setup() {
-    INVALID_CHARS="'[]/?!:\`.,()*\";{}+=<>~$|#@&–—"
+_usage() {
+    printf "
+Script to autogenerate markdown based on bash source code.\n
+The script generates table of contents and bashdoc and update it the given markdown template.\n
+Usage:\n %s [options.. ]\n
+Options:\n
+  -f | --file <filename.md> - Relative or absolute path to the README.md file.
+  -p | --sh-dir <folderpath> - path to the bash script source folder to generate shdocs.\n
+  -l | --toc-level <number> - Minimum level of header to print in Table of Contents.\n
+  -d | --toc-depth <number> - Maximum depth of tree to print in Table of Contents.\n
+  -h | --help - Display usage instructions.\n" "${0##*/}"
+    exit 0
+}
+
+_setup_arguments() {
+
+    unset MINLEVEL MAXLEVEL SCRIPT_FILE SOURCE_MARKDOWN SOURCE_SCRIPT_DIR
     MINLEVEL=1
     MAXLEVEL=3
-    SCRIPT_FILE=$(basename "${0}")
-    rm "$README"
-    cp readme-template.md "$README"
+    SCRIPT_FILE="${0##*/}"
+    SOURCE_MARKDOWN="../README.md"
+    SOURCE_SCRIPT_DIR="../src"
+
+    SHORTOPTS="hp:f:m:d:-:"
+
+    while getopts "${SHORTOPTS}" OPTION; do
+        case "${OPTION}" in
+            -)
+                _check_longoptions() { { [[ -z "$1" ]] && printf '%s: --%s: option requires an argument\nTry '"%s -h/--help"' for more information.\n' "${0##*/}" "${OPTARG}" "${0##*/}" && exit 1; } || :; }
+                case "${OPTARG}" in
+                    help)
+                        _usage
+                        ;;
+                    file)
+                        _check_longoptions "${!OPTIND}"
+                        SOURCE_MARKDOWN="${!OPTIND}" && OPTIND=$((OPTIND + 1))
+                        ;;
+                    toc-level)
+                        _check_longoptions "${!OPTIND}"
+                        MINLEVEL="${!OPTIND}" && OPTIND=$((OPTIND + 1))
+                        ;;
+                    toc-depth)
+                        _check_longoptions "${!OPTIND}"
+                        MAXLEVEL="${!OPTIND}" && OPTIND=$((OPTIND + 1))
+                        ;;
+                    sh-dir)
+                        _check_longoptions "${!OPTIND}"
+                        SOURCE_SCRIPT_DIR="${!OPTIND}" && OPTIND=$((OPTIND + 1))
+                        ;;
+                    '')
+                        _usage
+                        ;;
+                    *)
+                        printf '%s: --%s: Unknown option\nTry '"%s -h/--help"' for more information.\n' "${0##*/}" "${OPTARG}" "${0##*/}" && exit 1
+                        ;;
+                esac
+                ;;
+            h)
+                _usage
+                ;;
+            f)
+                SOURCE_MARKDOWN="${OPTARG}"
+                ;;
+            m)
+                MINLEVEL="${OPTARG}"
+                ;;
+            d)
+                MAXLEVEL="${OPTARG}"
+                ;;
+            p)
+                SOURCE_SCRIPT_DIR="${OPTARG}"
+                ;;
+            :)
+                printf '%s: -%s: option requires an argument\nTry '"%s -h/--help"' for more information.\n' "${0##*/}" "${OPTARG}" "${0##*/}" && exit 1
+                ;;
+            ?)
+                printf '%s: -%s: Unknown option\nTry '"%s -h/--help"' for more information.\n' "${0##*/}" "${OPTARG}" "${0##*/}" && exit 1
+                ;;
+        esac
+    done
+    shift "$((OPTIND - 1))"
+
+    if [[ -w "${SOURCE_MARKDOWN}" ]]; then
+        declare src_file src_extension
+        src_file="${SOURCE_MARKDOWN##*/}"
+        src_extension="${src_file##*.}"
+        if [[ "${src_extension,,}" != "md" ]]; then
+            printf "Provided file %s is not a markdown.\n" "${src_file}" && exit 1
+        fi
+    else
+        printf "Provided file %s does not exist or no enough permission to access it.\n" "${SOURCE_MARKDOWN}" && exit 1
+    fi
+
+    if [[ ! -d "${SOURCE_SCRIPT_DIR}" ]]; then
+        printf "Provided directory for bash script files %s does not exist.\n" "${SOURCE_SCRIPT_DIR}" && exit 1
+    fi
+
+    re='^[0-9]+$'
+    if ! [[ "${MINLEVEL}" =~ $re ]] || ! [[ "${MAXLEVEL}" =~ $re ]]; then
+        echo "error: Not a number" >&2
+        exit 1
+    fi
+    if [[ "${MINLEVEL}" -gt "${MAXLEVEL}" ]]; then
+        printf "Minimum level for TOC cannot be greater than the depth of TOC to be printed.\n" && exit 1
+    fi
+
 }
 
 _setup_tempfile() {
@@ -20,56 +118,64 @@ _setup_tempfile() {
 _generate_shdoc() {
     declare file
     file="$(realpath $1)"
-    ./shdoc.awk < $file >> "$2"
+    ./shdoc.awk < "${file}" >> "$2"
 }
 
 _insert_shdoc_to_file() {
-    declare shdoc_tmp_file="$1"
-    declare dest_file="$2"
+    declare shdoc_tmp_file source_markdown start_shdoc info_shdoc end_shdoc
+    shdoc_tmp_file="$1"
+    source_markdown="$2"
 
-    declare start_shdoc="<!-- START ${SCRIPT_FILE} generated SHDOC please keep comment here to allow auto update -->"
-    declare info_shdoc="<!-- DO NOT EDIT THIS SECTION, INSTEAD RE-RUN ${SCRIPT_FILE} TO UPDATE -->"
-    declare end_shdoc="<!-- END ${SCRIPT_FILE} generated SHDOC please keep comment here to allow auto update -->"
+    start_shdoc="<!-- START ${SCRIPT_FILE} generated SHDOC please keep comment here to allow auto update -->"
+    info_shdoc="<!-- DO NOT EDIT THIS SECTION, INSTEAD RE-RUN ${SCRIPT_FILE} TO UPDATE -->"
+    end_shdoc="<!-- END ${SCRIPT_FILE} generated SHDOC please keep comment here to allow auto update -->"
 
-    sed -i "1s/^/$info_shdoc\n/" "$shdoc_tmp_file"
+    sed -i "1s/^/${info_shdoc}\n/" "${shdoc_tmp_file}"
 
-    if grep --color=always -Pzl "(?s)$start_shdoc.*\n.*$end_shdoc" $dest_file &> /dev/null; then
+    if grep --color=always -Pzl "(?s)${start_shdoc}.*\n.*${end_shdoc}" $source_markdown &> /dev/null; then
         # src https://stackoverflow.com/questions/2699666/replace-delimited-block-of-text-in-file-with-the-contents-of-another-file
 
-        sed -i -ne "/$start_shdoc/ {p; r $shdoc_tmp_file" -e ":a; n; /$end_shdoc/ {p; b}; ba}; p" $dest_file
-        echo -e "\nUpdated shdoc content to $dest_file successfully\n"
+        sed -i -ne "/${start_shdoc}/ {p; r ${shdoc_tmp_file}" -e ":a; n; /${end_shdoc}/ {p; b}; ba}; p" "${source_markdown}"
+        echo -e "Updated shdoc content to ${source_markdown} successfully\n"
 
     else
-        printf "%s\n" "${start_shdoc}" >> "${dest_file}"
-        cat "${shdoc_tmp_file}" >> "${dest_file}"
-        printf "%s\n" "${end_shdoc}" >> "${dest_file}"
-        echo -e "\nCreated shdoc content to $dest_file successfully\n"
+        {
+            printf "%s\n" "${start_shdoc}"
+            cat "${shdoc_tmp_file}"
+            printf "%s\n" "${end_shdoc}"
+        } >> "${source_markdown}"
+        echo -e "Created shdoc content to ${source_markdown} successfully\n"
     fi
 }
 
 _process_sh_files() {
-    declare shdoc_tmp_file=$(_setup_tempfile)
-    find ../src -name '*.sh' -print0 | sort -z |
+    declare shdoc_tmp_file source_script_dir source_markdown
+    source_markdown="${1}"
+    source_script_dir="${2}"
+    shdoc_tmp_file=$(_setup_tempfile)
+    find "${source_script_dir}" -name '*.sh' -print0 | sort -z |
         while IFS= read -r -d '' line; do
-            _generate_shdoc "$line" "$shdoc_tmp_file"
+            _generate_shdoc "${line}" "${shdoc_tmp_file}"
         done
-    _insert_shdoc_to_file "$shdoc_tmp_file" "$README"
-    rm "$shdoc_tmp_file"
+    _insert_shdoc_to_file "${shdoc_tmp_file}" "${source_markdown}"
+    rm "${shdoc_tmp_file}"
 
 }
 
 _generate_toc() {
 
-    declare line level title anchor output counter temp_output
+    declare line level title anchor output counter temp_output invalid_chars
+
+    invalid_chars="'[]/?!:\`.,()*\";{}+=<>~$|#@&–—"
+    while IFS='' read -r line || [[ -n "${line}" ]]; do
+        level="$(echo "${line}" | sed -E 's/(#+).*/\1/; s/#/  /g; s/^  //')"
+        title="$(echo "${line}" | sed -E 's/^#+ //')"
+        [[ "${title}" = "Table of Contents" ]] && continue
 
-    while IFS='' read -r line || [[ -n "$line" ]]; do
-        level="$(echo "$line" | sed -E 's/(#+).*/\1/; s/#/  /g; s/^  //')"
-        title="$(echo "$line" | sed -E 's/^#+ //')"
         # tr does not do OK the lowercase for non ascii chars, add sed to pipeline -> src https://stackoverflow.com/questions/13381746/tr-upper-lower-with-cyrillic-text
-        anchor="$(echo "$title" | tr '[:upper:] ' '[:lower:]-' | sed 's/[[:upper:]]*/\L&/' | tr -d "$INVALID_CHARS")"
+        anchor="$(echo "${title}" | tr '[:upper:] ' '[:lower:]-' | sed 's/[[:upper:]]*/\L&/' | tr -d "${invalid_chars}")"
 
         # check new line introduced is not duplicated, if is duplicated, introduce a number at the end
-        #   copying doctoc behavior
         temp_output=$output"$level- [$title](#$anchor)\n"
         counter=1
         while true; do
@@ -86,7 +192,7 @@ _generate_toc() {
 
         # grep: filter header candidates to be included in toc
         # sed: remove the ignored headers (case: minlevel greater than one) to avoid unnecessary spacing later in level variable assignment
-    done <<< "$(grep -E "^#{${MINLEVEL},${MAXLEVEL}} " "$1" | tr -d '\r' | sed "s/^#\{$(($MINLEVEL - 1))\}//g")"
+    done <<< "$(grep -E "^#{${MINLEVEL},${MAXLEVEL}} " "${1}" | tr -d '\r' | sed "s/^#\{$((${MINLEVEL} - 1))\}//g")"
 
     # when in toc we have two `--` quit one
     output="$(echo "$output" | sed 's/--*/-/g')"
@@ -97,63 +203,68 @@ _generate_toc() {
 
 _insert_toc_to_file() {
 
-    declare toc_text="$2"
+    declare source_markdown toc_text start_toc info_toc end_toc utext_ampersand utext_slash
+    source_markdown="${1}"
+    toc_text="${2}"
 
-    # inspired in doctoc lines
-    declare start_toc="<!-- START ${SCRIPT_FILE} generated TOC please keep comment here to allow auto update -->"
-    declare info_toc="<!-- DO NOT EDIT THIS SECTION, INSTEAD RE-RUN ${SCRIPT_FILE} TO UPDATE -->"
-    declare end_toc="<!-- END ${SCRIPT_FILE} generated TOC please keep comment here to allow auto update -->"
+    start_toc="<!-- START ${SCRIPT_FILE} generated TOC please keep comment here to allow auto update -->"
+    info_toc="<!-- DO NOT EDIT THIS SECTION, INSTEAD RE-RUN ${SCRIPT_FILE} TO UPDATE -->"
+    end_toc="<!-- END ${SCRIPT_FILE} generated TOC please keep comment here to allow auto update -->"
 
     toc_block="$start_toc\n$info_toc\n## Table of Contents\n\n$toc_text\n$end_toc"
 
     # temporary replace of '/' (confused with separator of substitutions) and '&' (confused with match regex symbol) to run the special sed command
     utext_ampersand="id8234923000230gzz"
     utext_slash="id9992384923423gzz"
-    toc_block="$(echo "$toc_block" | sed "s,\&,$utext_ampersand,g")"
-    toc_block="$(echo "$toc_block" | sed "s,\/,$utext_slash,g")"
+    toc_block="$(echo "${toc_block}" | sed "s,\&,${utext_ampersand},g")"
+    toc_block="$(echo "${toc_block}" | sed "s,\/,${utext_slash},g")"
 
     # search multiline toc block -> https://stackoverflow.com/questions/2686147/how-to-find-patterns-across-multiple-lines-using-grep/2686705
     # grep color for debugging -> https://superuser.com/questions/914856/grep-display-all-output-but-highlight-search-matches
-    if grep --color=always -Pzl "(?s)$start_toc.*\n.*$end_toc" $1 &> /dev/null; then
+    if grep --color=always -Pzl "(?s)${start_toc}.*\n.*${end_toc}" "${source_markdown}" &> /dev/null; then
         # src https://askubuntu.com/questions/533221/how-do-i-replace-multiple-lines-with-single-word-in-fileinplace-replace
-        sed -i ":a;N;\$!ba;s/$start_toc.*$end_toc/$toc_block/g" $1
-        echo -e "\nUpdated TOC content in $1 succesfully\n"
+        sed -i ":a;N;\$!ba;s/$start_toc.*$end_toc/$toc_block/g" "${source_markdown}"
+        echo -e "Updated TOC content in ${source_markdown} succesfully\n"
 
     else
-        sed -i 1i"$toc_block" "$1"
-        echo -e "\nCreated TOC in $1 succesfully\n"
+        sed -i 1i"$toc_block" "${source_markdown}"
+        echo -e "Created TOC in ${source_markdown} succesfully\n"
 
     fi
 
     # undo symbol replacements
-    sed -i "s,$utext_ampersand,\&,g" $1
-    sed -i "s,$utext_slash,\/,g" $1
+    sed -i "s,${utext_ampersand},\&,g" "${source_markdown}"
+    sed -i "s,${utext_slash},\/,g" "${source_markdown}"
 
 }
 
 _process_toc() {
-    declare toc_temp_file=$(_setup_tempfile)
+    declare toc_temp_file source_markdown
+    source_markdown="${1}"
 
-    sed '/```/,/```/d' "$README" > "$toc_temp_file"
+    toc_temp_file=$(_setup_tempfile)
+
+    sed '/```/,/```/d' "${source_markdown}" > "${toc_temp_file}"
 
     declare level=$MINLEVEL
-    while [[ $(grep -E "^#{$level} " "$toc_temp_file" | wc -l) -le 1 ]]; do
+    while [[ $(grep -E "^#{$level} " "${toc_temp_file}" | wc -l) -le 1 ]]; do
         level=$(($level + 1))
     done
-    if [[ $MINLEVEL -ne $level ]]; then
-        echo -e "\nnote: detected all headers (maybe except 1) in level $level, switching to that level of headers to fill table of contents"
-    fi
-    MINLEVEL=$level
-    toc_text=$(_generate_toc "$toc_temp_file")
-    rm "$toc_temp_file"
 
-    _insert_toc_to_file "$README" "$toc_text"
+    MINLEVEL=${level}
+    toc_text=$(_generate_toc "${toc_temp_file}")
+    rm "${toc_temp_file}"
+
+    _insert_toc_to_file "${source_markdown}" "${toc_text}"
 }
 
 main() {
-    _setup
-    _process_sh_files
-    _process_toc
+    trap 'exit "$?"' INT TERM && trap 'exit "$?"' EXIT
+    set -o errexit -o noclobber -o pipefail
+
+    _setup_arguments "${@}"
+    _process_sh_files "${SOURCE_MARKDOWN}" "${SOURCE_SCRIPT_DIR}"
+    _process_toc "${SOURCE_MARKDOWN}" "${MINLEVEL}" "${MAXLEVEL}"
 }
 
-main "$@"
+main "${@}"