diff --git a/install.sh b/install.sh
index 23724a1..cd8745d 100644
--- a/install.sh
+++ b/install.sh
@@ -1,10 +1,10 @@
-#!/usr/bin/env bash
+#!/bin/sh
 
 # This script will install the latest version of Mailpit.
 
 # Check dependencias is installed
 for cmd in curl tar; do
-    if ! command -v "$cmd" &>/dev/null; then
+    if ! command -v "$cmd" >/dev/null 2>&1; then
         echo "Then $cmd command is required but not installed."
         echo "Please install $cmd and try again."
         exit 1
@@ -42,58 +42,75 @@ esac
 
 GH_REPO="axllent/mailpit"
 INSTALL_PATH="/usr/local/bin"
-TIMEOUT=90 # --max-time in curl
-
-# The arguments in extended format for the curl command.
-CURL_ARGS=(
-    "--silent"
-    "--fail"
-    "--location"
-    "--max-time" "$TIMEOUT"
-)
+TIMEOUT=90
 # This is used to authenticate with the GitHub API. (Fix the public rate limiting issue)
-AUTH_TOKEN="${GITHUB_TOKEN:-}"
+# Try the GITHUB_TOKEN environment variable is set globally.
+GITHUB_API_TOKEN="${GITHUB_TOKEN:-}"
 
 # Update the default values if the user has set.
-while [[ $# -gt 0 ]]; do
+while [ $# -gt 0 ]; do
     case $1 in
     --install-path)
         shift
-        INSTALL_PATH="$1"
+        case "$1" in
+        */*)
+            # Remove trailing slashes from the path.
+            INSTALL_PATH="$(echo "$1" | sed 's#/\+$##')"
+            [ -z "$INSTALL_PATH" ] && INSTALL_PATH="/"
+            ;;
+        esac
         ;;
     --auth | --auth-token | --github-token | --token)
         shift
-        [[ "${1:-}" =~ ^- ]] || AUTH_TOKEN="$1"
+        case "$1" in
+        gh*)
+            GITHUB_API_TOKEN="$1"
+            ;;
+        esac
         ;;
     *) ;;
     esac
     shift
 done
 
-# Set the header auth if the user has set a GitHub token.
-if [[ -n "$AUTH_TOKEN" ]] && [[ "$AUTH_TOKEN" =~ ^gh[pousr]_[A-Za-z0-9_]{36,251}$ ]]; then
-    CURL_ARGS+=("--header" "Authorization: 'Bearer $AUTH_TOKEN'")
+# Description of the sort parameters for curl command.
+# -s: Silent mode.
+# -f: Fail silently on server errors.
+# -L: Follow redirects.
+# -m: Set maximum time allowed for the transfer.
+
+if [ -n "$GITHUB_API_TOKEN" ] && [ "${#GITHUB_API_TOKEN}" -gt 36 ]; then
+    CURL_OUTPUT="$(curl -sfL -m $TIMEOUT -H "Authorization: Bearer $GITHUB_API_TOKEN" https://api.github.com/repos/${GH_REPO}/releases/latest)"
+    EXIT_CODE=$?
+else
+    CURL_OUTPUT="$(curl --sfL -m $TIMEOUT https://api.github.com/repos/${GH_REPO}/releases/latest)"
+    EXIT_CODE=$?
 fi
 
-CURL_OUTPUT=$(curl "${CURL_ARGS[@]}" "https://api.github.com/repos/${GH_REPO}/releases/latest")
-EXIT_CODE=$?
-if [[ $EXIT_CODE -eq 0 ]]; then
+VERSION=""
+if [ $EXIT_CODE -eq 0 ]; then
     # Extracts the latest version using jq, awk, or sed.
-    if command -v jq &>/dev/null; then
-        VERSION=$(echo "$CURL_OUTPUT" | jq -r '.tag_name')
-    elif command -v awk &>/dev/null; then
+    if command -v jq >/dev/null 2>&1; then
+        # Use jq -n because the output is not a valid JSON in sh.
+        VERSION=$(jq -n "$CURL_OUTPUT" | jq -r '.tag_name')
+    elif command -v awk >/dev/null 2>&1; then
         VERSION=$(echo "$CURL_OUTPUT" | awk -F: '$1 ~ /tag_name/ {gsub(/[^v0-9\.]+/, "", $2) ;print $2; exit}')
-    else
+    elif command -v sed >/dev/null 2>&1; then
         VERSION=$(echo "$CURL_OUTPUT" | sed -n 's/.*"tag_name": *"\([^"]*\)".*/\1/p')
+    else
+        EXIT_CODE=3
     fi
 fi
 
 # Validate the version.
-if ! [[ "$VERSION" =~ ^v[0-9]{1,}[0-9\.]+$ ]]; then
+case "$VERSION" in
+v[0-9][0-9\.]*) ;;
+*)
     echo "There was an error trying to check what is the latest version of Mailpit."
     echo "Please try again later."
     exit $EXIT_CODE
-fi
+    ;;
+esac
 
 TEMP_DIR="$(mktemp -qd)"
 EXIT_CODE=$?
@@ -104,33 +121,64 @@ if [ -z "$TEMP_DIR" ] || [ ! -d "$TEMP_DIR" ]; then
 fi
 
 GH_REPO_BIN="mailpit-${OS}-${OS_ARCH}.tar.gz"
-CURL_ARGS+=("--output" "${GH_REPO_BIN}")
-
-if ! cd "$TEMP_DIR"; then
-    EXIT_CODE=$?
-    echo "ERROR: Changing to temporary directory."
+if [ "$INSTALL_PATH" = "/" ]; then
+    INSTALL_BIN_PATH="/mailpit"
 else
+    INSTALL_BIN_PATH="${INSTALL_PATH}/mailpit"
+fi
+cd "$TEMP_DIR" || EXIT_CODE=$?
+if [ $EXIT_CODE -eq 0 ]; then
     # Download the latest release.
-    curl "${CURL_ARGS[@]}" "https://github.com/${GH_REPO}/releases/download/${VERSION}/${GH_REPO_BIN}"
+    #
+    # Description of the sort parameters for curl command.
+    # -s: Silent mode.
+    # -f: Fail silently on server errors.
+    # -L: Follow redirects.
+    # -m: Set maximum time allowed for the transfer.
+    # -o: Write output to a file instead of stdout.
+    curl -sfL -m $TIMEOUT -o "${GH_REPO_BIN}" "https://github.com/${GH_REPO}/releases/download/${VERSION}/${GH_REPO_BIN}"
     EXIT_CODE=$?
 
     # The following conditions check each step of the installation.
     # If there is an error in any of the steps, an error message is printed.
 
-    if ! [[ -f "${GH_REPO_BIN}" ]]; then
-        echo "ERROR: Downloading latest release."
-    elif ! tar zxf "$GH_REPO_BIN"; then
+    if [ $EXIT_CODE -eq 0 ]; then
+        if ! [ -f "${GH_REPO_BIN}" ]; then
+            EXIT_CODE=1
+            echo "ERROR: Downloading latest release."
+        fi
+    fi
+
+    if [ $EXIT_CODE -eq 0 ]; then
+        tar zxf "$GH_REPO_BIN"
         EXIT_CODE=$?
-        echo "ERROR: Extracting \"${GH_REPO_BIN}\"."
-    elif ! mkdir -p "${INSTALL_PATH}"; then
+        if [ $EXIT_CODE -ne 0 ]; then
+            echo "ERROR: Extracting \"${GH_REPO_BIN}\"."
+        fi
+    fi
+
+    if [ $EXIT_CODE -eq 0 ] && [ ! -d "$INSTALL_PATH" ]; then
+        mkdir -p "${INSTALL_PATH}"
         EXIT_CODE=$?
-        echo "ERROR: Creating \"${INSTALL_PATH}\" directory."
-    elif ! cp -f mailpit "${INSTALL_PATH}"; then
+        if [ $EXIT_CODE -ne 0 ]; then
+            echo "ERROR: Creating \"${INSTALL_PATH}\" directory."
+        fi
+    fi
+
+    if [ $EXIT_CODE -eq 0 ]; then
+        cp mailpit "$INSTALL_BIN_PATH"
         EXIT_CODE=$?
-        echo "ERROR: Copying mailpit to \"${INSTALL_PATH}\" directory."
-    elif ! chmod 755 "${INSTALL_PATH}/mailpit"; then
+        if [ $EXIT_CODE -ne 0 ]; then
+            echo "ERROR: Copying mailpit to \"${INSTALL_PATH}\" directory."
+        fi
+    fi
+
+    if [ $EXIT_CODE -eq 0 ]; then
+        chmod 755 "$INSTALL_BIN_PATH"
         EXIT_CODE=$?
-        echo "ERROR: Setting permissions for \"${INSTALL_PATH}/mailpit\" binary."
+        if [ $EXIT_CODE -ne 0 ]; then
+            echo "ERROR: Setting permissions for \"$INSTALL_BIN_PATH\" binary."
+        fi
     fi
 
     # Set the owner and group to root:root if the script is run as root.
@@ -143,20 +191,25 @@ else
         *) ;;
         esac
 
-        if ! chown "${OWNER}:${GROUP}" "${INSTALL_PATH}/mailpit"; then
-            EXIT_CODE=$?
-            echo "ERROR: Setting ownership for \"${INSTALL_PATH}/mailpit\" binary."
+        chown "${OWNER}:${GROUP}" "$INSTALL_BIN_PATH"
+        EXIT_CODE=$?
+        if [ $EXIT_CODE -ne 0 ]; then
+            echo "ERROR: Setting ownership for \"$INSTALL_BIN_PATH\" binary."
         fi
     fi
+else
+    echo "ERROR: Changing to temporary directory."
+    exit $EXIT_CODE
 fi
 
 # Cleanup the temporary directory.
 rm -rf "$TEMP_DIR"
 # Check the EXIT_CODE variable, and print the success or error message.
-if [[ $EXIT_CODE -eq 0 ]]; then
-    echo "Installed successfully to \"${INSTALL_PATH}/mailpit\""
-else
+if [ $EXIT_CODE -ne 0 ]; then
     echo "There was an error installing Mailpit."
     echo "Please try again later."
+    exit $EXIT_CODE
 fi
-exit $EXIT_CODE
+
+echo "Installed successfully to \"$INSTALL_BIN_PATH\"."
+exit 0