diff --git a/agent/src/main/java/com/taobao/arthas/agent/AgentBootstrap.java b/agent/src/main/java/com/taobao/arthas/agent/AgentBootstrap.java
index 8cc68d96..adbba79d 100644
--- a/agent/src/main/java/com/taobao/arthas/agent/AgentBootstrap.java
+++ b/agent/src/main/java/com/taobao/arthas/agent/AgentBootstrap.java
@@ -100,7 +100,7 @@ public class AgentBootstrap {
             args = decodeArg(args);
             int index = args.indexOf(';');
             String agentJar = args.substring(0, index);
-            final String agentArgs = args.substring(index, args.length());
+            final String agentArgs = args.substring(index);
 
             File agentJarFile = new File(agentJar);
             if (!agentJarFile.exists()) {
diff --git a/bin/install.sh b/bin/install.sh
index 46cd0488..e2c77ba6 100644
--- a/bin/install.sh
+++ b/bin/install.sh
@@ -22,9 +22,9 @@ exit_on_err()
 }
 
 # check permission to download && install
-[ ! -w ./ ] && exit_on_err 1 "permission denied, target directory ./ was not writable."
+[[ ! -w ./ ]] && exit_on_err 1 "permission denied, target directory ./ was not writable."
 
-if [ $# -gt 1 ] && [ $1 = "--url" ]; then
+if [[ $# -gt 1 ]] && [[ $1 = "--url" ]]; then
   shift
   ARTHAS_FILE_URL=$1
   shift
@@ -35,14 +35,14 @@ echo "downloading... ${TEMP_ARTHAS_FILE}"
 curl \
     -sLk \
     --connect-timeout ${SO_TIMEOUT} \
-    $ARTHAS_FILE_URL \
+    ${ARTHAS_FILE_URL} \
     -o ${TEMP_ARTHAS_FILE} \
 || exit_on_err 1 "download failed!"
 
-# wirte or overwrite local file
+# write or overwrite local file
 rm -rf as.sh
 mv ${TEMP_ARTHAS_FILE} ${TARGET_ARTHAS_FILE}
 chmod +x ${TARGET_ARTHAS_FILE}
 
 # done
-echo "Arthas install successed."
+echo "Arthas install succeeded."
diff --git a/boot/src/main/java/com/taobao/arthas/boot/Bootstrap.java b/boot/src/main/java/com/taobao/arthas/boot/Bootstrap.java
index 60eb01af..3e9d0809 100644
--- a/boot/src/main/java/com/taobao/arthas/boot/Bootstrap.java
+++ b/boot/src/main/java/com/taobao/arthas/boot/Bootstrap.java
@@ -76,7 +76,7 @@ public class Bootstrap {
      * <pre>
      * The directory contains arthas-core.jar/arthas-client.jar/arthas-spy.jar.
      * 1. When use-version is not empty, try to find arthas home under ~/.arthas/lib
-     * 2. Try set the directory where arthas-boot.jar is located to arhtas home
+     * 2. Try set the directory where arthas-boot.jar is located to arthas home
      * 3. Try to download from maven repo
      * </pre>
      */
@@ -524,7 +524,7 @@ public class Bootstrap {
     private static void verifyArthasHome(String arthasHome) {
         File home = new File(arthasHome);
         if (home.isDirectory()) {
-            String fileList[] = { "arthas-core.jar", "arthas-agent.jar", "arthas-spy.jar" };
+            String[] fileList = { "arthas-core.jar", "arthas-agent.jar", "arthas-spy.jar" };
 
             for (String fileName : fileList) {
                 if (!new File(home, fileName).exists()) {