diff --git a/codes/linux/ops/main.sh b/codes/linux/ops/main.sh
index 5f09006..d7c1f62 100644
--- a/codes/linux/ops/main.sh
+++ b/codes/linux/ops/main.sh
@@ -26,13 +26,13 @@ function checkOsVersion(){
   if(($1 == 1))
   then
     platform=`uname -i`
-    if [[ ${platform} != "x86_64" ]];then
+    if [[ ${platform} != "x86_64" ]]; then
     echo "this script is only for 64bit Operating System !"
     exit 1
     fi
     echo "the platform is ok"
     version=`lsb_release -r |awk '{print substr($2,1,1)}'`
-    if [[ ${version} != 6 ]];then
+    if [[ ${version} != 6 ]]; then
     echo "this script is only for CentOS 6 !"
     exit 1
     fi
diff --git a/codes/shell/operator/operator-demo2.sh b/codes/shell/operator/operator-demo2.sh
index 05cd0b2..1ebc849 100644
--- a/codes/shell/operator/operator-demo2.sh
+++ b/codes/shell/operator/operator-demo2.sh
@@ -12,7 +12,7 @@ fi
 
 echo "x=${x}, y=${y}"
 
-if [[ ${x} -eq ${y} ]];then
+if [[ ${x} -eq ${y} ]]; then
    echo "${x} -eq ${y} : x 等于 y"
 else
    echo "${x} -eq ${y}: x 不等于 y"
diff --git a/codes/shell/operator/operator-demo3.sh b/codes/shell/operator/operator-demo3.sh
index 68dc499..e127fa5 100644
--- a/codes/shell/operator/operator-demo3.sh
+++ b/codes/shell/operator/operator-demo3.sh
@@ -12,25 +12,25 @@ fi
 
 echo "x=${x}, y=${y}"
 
-if [[ ${x} != ${y} ]];then
+if [[ ${x} != ${y} ]]; then
    echo "${x} != ${y} : x 不等于 y"
 else
    echo "${x} != ${y}: x 等于 y"
 fi
 
-if [[ ${x} -lt 100 && ${y} -gt 15 ]];then
+if [[ ${x} -lt 100 && ${y} -gt 15 ]]; then
    echo "${x} 小于 100 且 ${y} 大于 15 : 返回 true"
 else
    echo "${x} 小于 100 且 ${y} 大于 15 : 返回 false"
 fi
 
-if [[ ${x} -lt 100 || ${y} -gt 100 ]];then
+if [[ ${x} -lt 100 || ${y} -gt 100 ]]; then
    echo "${x} 小于 100 或 ${y} 大于 100 : 返回 true"
 else
    echo "${x} 小于 100 或 ${y} 大于 100 : 返回 false"
 fi
 
-if [[ ${x} -lt 5 || ${y} -gt 100 ]];then
+if [[ ${x} -lt 5 || ${y} -gt 100 ]]; then
    echo "${x} 小于 5 或 ${y} 大于 100 : 返回 true"
 else
    echo "${x} 小于 5 或 ${y} 大于 100 : 返回 false"
diff --git a/codes/shell/operator/operator-demo5.sh b/codes/shell/operator/operator-demo5.sh
index 828803c..b4ee6bd 100644
--- a/codes/shell/operator/operator-demo5.sh
+++ b/codes/shell/operator/operator-demo5.sh
@@ -12,31 +12,31 @@ fi
 
 echo "x=${x}, y=${y}"
 
-if [[ ${x} = ${y} ]];then
+if [[ ${x} = ${y} ]]; then
    echo "${x} = ${y} : x 等于 y"
 else
    echo "${x} = ${y}: x 不等于 y"
 fi
 
-if [[ ${x} != ${y} ]];then
+if [[ ${x} != ${y} ]]; then
    echo "${x} != ${y} : x 不等于 y"
 else
    echo "${x} != ${y}: x 等于 y"
 fi
 
-if [[ -z ${x} ]];then
+if [[ -z ${x} ]]; then
    echo "-z ${x} : 字符串长度为 0"
 else
    echo "-z ${x} : 字符串长度不为 0"
 fi
 
-if [[ -n "${x}" ]];then
+if [[ -n "${x}" ]]; then
    echo "-n ${x} : 字符串长度不为 0"
 else
    echo "-n ${x} : 字符串长度为 0"
 fi
 
-if [[ ${x} ]];then
+if [[ ${x} ]]; then
    echo "${x} : 字符串不为空"
 else
    echo "${x} : 字符串为空"
diff --git a/codes/shell/operator/operator-demo6.sh b/codes/shell/operator/operator-demo6.sh
index 954d84e..9c810eb 100644
--- a/codes/shell/operator/operator-demo6.sh
+++ b/codes/shell/operator/operator-demo6.sh
@@ -2,37 +2,37 @@
 
 file="/etc/hosts"
 
-if [[ -r ${file} ]];then
+if [[ -r ${file} ]]; then
    echo "${file} 文件可读"
 else
    echo "${file} 文件不可读"
 fi
-if [[ -w ${file} ]];then
+if [[ -w ${file} ]]; then
    echo "${file} 文件可写"
 else
    echo "${file} 文件不可写"
 fi
-if [[ -x ${file} ]];then
+if [[ -x ${file} ]]; then
    echo "${file} 文件可执行"
 else
    echo "${file} 文件不可执行"
 fi
-if [[ -f ${file} ]];then
+if [[ -f ${file} ]]; then
    echo "${file} 文件为普通文件"
 else
    echo "${file} 文件为特殊文件"
 fi
-if [[ -d ${file} ]];then
+if [[ -d ${file} ]]; then
    echo "${file} 文件是个目录"
 else
    echo "${file} 文件不是个目录"
 fi
-if [[ -s ${file} ]];then
+if [[ -s ${file} ]]; then
    echo "${file} 文件不为空"
 else
    echo "${file} 文件为空"
 fi
-if [[ -e ${file} ]];then
+if [[ -e ${file} ]]; then
    echo "${file} 文件存在"
 else
    echo "${file} 文件不存在"
diff --git a/codes/shell/statement/break-demo.sh b/codes/shell/statement/break-demo.sh
new file mode 100644
index 0000000..eba7c16
--- /dev/null
+++ b/codes/shell/statement/break-demo.sh
@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+
+# 查找 10 以内第一个能整除 2 和 3 的正整数
+i=1
+while [[ ${i} -lt 10 ]]; do
+  if [[ $((i % 3)) -eq 0 ]] && [[ $((i % 2)) -eq 0 ]]; then
+    echo ${i}
+    break;
+  fi
+  i=`expr ${i} + 1`
+done
+# Output: 6
diff --git a/codes/shell/statement/case-demo.sh b/codes/shell/statement/case-demo.sh
new file mode 100644
index 0000000..d8302ed
--- /dev/null
+++ b/codes/shell/statement/case-demo.sh
@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+
+echo "input param: " $1 $2 $3
+
+x=0
+if [[ -n $1 ]]; then
+  x=$1
+fi
+
+y=0
+if [[ -n $2 ]]; then
+  y=$2
+fi
+
+oper=""
+if [[ -n $3 ]]; then
+  oper=$3
+fi
+
+exec
+case ${oper} in
+  "+")
+    val=`expr ${x} + ${y}`
+    echo "${x} + ${y} = ${val}"
+  ;;
+  "-")
+    val=`expr ${x} - ${y}`
+    echo "${x} - ${y} = ${val}"
+  ;;
+  "*")
+    val=`expr ${x} \* ${y}`
+    echo "${x} * ${y} = ${val}"
+  ;;
+  "/")
+    val=`expr ${x} / ${y}`
+    echo "${x} / ${y} = ${val}"
+  ;;
+  *)
+    echo "Unknown oper!"
+  ;;
+esac
diff --git a/codes/shell/statement/caseDemo.sh b/codes/shell/statement/caseDemo.sh
deleted file mode 100644
index e74d89c..0000000
--- a/codes/shell/statement/caseDemo.sh
+++ /dev/null
@@ -1,18 +0,0 @@
-#!/usr/bin/env bash
-
-echo "input param: " $1
-
-case $1 in
-  "jpg" | "jpeg")
-    echo "It's image with jpeg extension."
-  ;;
-  "png")
-    echo "It's image with png extension."
-  ;;
-  "gif")
-    echo "Oh, it's a giphy!"
-  ;;
-  *)
-    echo "Woops! It's not image!"
-  ;;
-esac
diff --git a/codes/shell/statement/continueDemo.sh b/codes/shell/statement/continue-demo.sh
similarity index 80%
rename from codes/shell/statement/continueDemo.sh
rename to codes/shell/statement/continue-demo.sh
index 3b63c50..035d95c 100644
--- a/codes/shell/statement/continueDemo.sh
+++ b/codes/shell/statement/continue-demo.sh
@@ -7,3 +7,9 @@ for (( i = 0; i < 10; i ++ )); do
   fi
   echo ${i}
 done
+#  Output:
+#  1
+#  3
+#  5
+#  7
+#  9
diff --git a/codes/shell/statement/for-demo.sh b/codes/shell/statement/for-demo.sh
new file mode 100644
index 0000000..ba1aec9
--- /dev/null
+++ b/codes/shell/statement/for-demo.sh
@@ -0,0 +1,37 @@
+#!/usr/bin/env bash
+
+################### for 语句 ###################
+echo "print 0 to 9"
+for (( j = 0; j < 10; j ++ )); do
+  echo ${j}
+done
+#  Output:
+#  print 0 to 9
+#  0
+#  1
+#  2
+#  3
+#  4
+#  5
+#  6
+#  7
+#  8
+#  9
+
+################### for in 语句 ###################
+echo "print 1 to 5"
+for i in {1..5}; do echo ${i}; done
+#  Output:
+#  print 1 to 5
+#  1
+#  2
+#  3
+#  4
+#  5
+
+################### for in 语句遍历文件 ###################
+DIR=/home/zp
+for FILE in ${DIR}/*.sh; do
+  mv "$FILE" "${DIR}/scripts"
+done
+# 将 /home/zp 目录下所有 sh 文件拷贝到 /home/zp/scripts
diff --git a/codes/shell/statement/forDemo.sh b/codes/shell/statement/forDemo.sh
deleted file mode 100644
index f1e70cc..0000000
--- a/codes/shell/statement/forDemo.sh
+++ /dev/null
@@ -1,11 +0,0 @@
-#!/usr/bin/env bash
-
-echo "print 1 to 5"
-for i in {1..5}; do
-  echo $i;
-done
-
-echo "print 0 to 9"
-for (( i = 0; i < 10; i ++ )); do
-  echo $i
-done
diff --git a/codes/shell/statement/forDemo02.sh b/codes/shell/statement/forDemo02.sh
deleted file mode 100644
index 7d7a4f2..0000000
--- a/codes/shell/statement/forDemo02.sh
+++ /dev/null
@@ -1,6 +0,0 @@
-#!/usr/bin/env bash
-
-for FILE in $HOME/; do
-  mv "$FILE" "./"
-  chmod +x "./${FILE}"
-done
diff --git a/codes/shell/statement/if-demo.sh b/codes/shell/statement/if-demo.sh
new file mode 100644
index 0000000..62b7031
--- /dev/null
+++ b/codes/shell/statement/if-demo.sh
@@ -0,0 +1,33 @@
+#!/usr/bin/env bash
+
+################### if 语句 ###################
+# 写成一行
+if [[ 1 -eq 1 ]]; then echo "1 -eq 1 result is: true"; fi
+# Output: 1 -eq 1 result is: true
+
+# 写成多行
+if [[ "abc" -eq "abc" ]]
+then
+  echo ""abc" -eq "abc" result is: true"
+fi
+# Output: abc -eq abc result is: true
+
+################### if else 语句 ###################
+if [[ 2 -ne 1 ]]; then
+  echo "true"
+else
+  echo "false"
+fi
+# Output: true
+
+################### if elif else 语句 ###################
+x=10
+y=20
+if [[ ${x} > ${y} ]]; then
+   echo "${x} > ${y}"
+elif [[ ${x} < ${y} ]]; then
+   echo "${x} < ${y}"
+else
+   echo "${x} = ${y}"
+fi
+# Output: 10 < 20
diff --git a/codes/shell/statement/ifDemo.sh b/codes/shell/statement/ifDemo.sh
deleted file mode 100644
index 33b417b..0000000
--- a/codes/shell/statement/ifDemo.sh
+++ /dev/null
@@ -1,27 +0,0 @@
-#!/usr/bin/env bash
-
-if [[ -z $1 ]]; then
-  echo "please input first param";
-  exit
-fi
-
-if [[ -z $2 ]]; then
-  echo "please input second param";
-  exit
-fi
-
-if [[ $1 > $2 ]]; then
-  echo "\$1 > \$2";
-elif [[ $1 < $2 ]]; then
-  echo "\$1 < \$2";
-else
-  echo "\$1 != \$2";
-fi
-
-# execute: ./ifDemo.sh abc abc
-# output:
-# $1 == $2
-
-# execute: ./ifDemo.sh abc ab
-# output:
-# $1 != $2
diff --git a/codes/shell/statement/selectDemo.sh b/codes/shell/statement/select-demo.sh
similarity index 91%
rename from codes/shell/statement/selectDemo.sh
rename to codes/shell/statement/select-demo.sh
index e4e6d41..956ac8f 100644
--- a/codes/shell/statement/selectDemo.sh
+++ b/codes/shell/statement/select-demo.sh
@@ -10,5 +10,5 @@ case ${ITEM} in
   gem) gem install ${PACKAGE} ;;
   pip) pip install ${PACKAGE} ;;
 esac
-break ### 避免无限循环
+break # 避免无限循环
 done
diff --git a/codes/shell/statement/until-demo.sh b/codes/shell/statement/until-demo.sh
new file mode 100644
index 0000000..320b590
--- /dev/null
+++ b/codes/shell/statement/until-demo.sh
@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+
+x=0
+until [[ ${x} -ge 5 ]]; do
+  echo ${x}
+  x=`expr ${x} + 1`
+done
+#  Output:
+#  0
+#  1
+#  2
+#  3
+#  4
diff --git a/codes/shell/statement/whileDemo.sh b/codes/shell/statement/while-demo.sh
similarity index 60%
rename from codes/shell/statement/whileDemo.sh
rename to codes/shell/statement/while-demo.sh
index 089eab0..375bed9 100644
--- a/codes/shell/statement/whileDemo.sh
+++ b/codes/shell/statement/while-demo.sh
@@ -5,5 +5,16 @@ x=0
 ### x小于10
 while [[ ${x} -lt 10 ]]; do
   echo $((x * x))
-  x=$((x + 1)) ### x加1
+  x=$((x + 1))
 done
+#  Output:
+#  0
+#  1
+#  4
+#  9
+#  16
+#  25
+#  36
+#  49
+#  64
+#  81