✨ 添加示例

codes/bash/statement/caseDemo.sh

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+#!/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

codes/bash/statement/continueDemo.sh

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+#!/usr/bin/env bash
+
+# 打印10以内的奇数
+for (( i = 0; i < 10; i ++ )); do
+  if [[ $((i % 2)) -eq 0 ]]; then
+    continue;
+  fi
+  echo ${i}
+done

codes/bash/statement/forDemo.sh

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+#!/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

codes/bash/statement/forDemo02.sh

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+#!/usr/bin/env bash
+
+for FILE in $HOME/; do
+  mv "$FILE" "./"
+  chmod +x "./${FILE}"
+done

codes/bash/statement/ifDemo.sh

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+#!/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";
+else
+  echo "\$1 != \$2";
+fi
+
+# execute: ./ifDemo.sh abc abc
+# output:
+# $1 == $2
+
+# execute: ./ifDemo.sh abc ab
+# output:
+# $1 != $2

codes/bash/statement/selectDemo.sh

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+#!/usr/bin/env bash
+
+PS3="Choose the package manager: "
+select ITEM in bower npm gem pip
+do
+echo -n "Enter the package name: " && read PACKAGE
+case ${ITEM} in
+  bower) bower install ${PACKAGE} ;;
+  npm) npm install ${PACKAGE} ;;
+  gem) gem install ${PACKAGE} ;;
+  pip) pip install ${PACKAGE} ;;
+esac
+break ### 避免无限循环
+done

codes/bash/statement/whileDemo.sh

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+#!/usr/bin/env bash
+
+### 0到9之间每个数的平方
+x=0
+### x小于10
+while [[ ${x} -lt 10 ]]; do
+  echo $((x * x))
+  x=$((x + 1)) ### x加1
+done

codes/bash/variable/positionalVariableDemo.sh

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+#!/usr/bin/env bash
+
+### 如果变量为空，赋给他们默认值
+: ${VAR:='default'}
+: ${1:='first'}
+echo "\$1 : " $1
+: ${2:='second'}
+echo "\$2 : " $2
+
+### 或者
+FOO=${FOO:-'default'}
+echo "FOO : " ${FOO}
+
+# execute: ./positionalVariableDemo.sh big small
+# output:
+# $1 :  big
+# $2 :  small
+# FOO :  default

codes/bash/variable/variableDemo.sh

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+#!/usr/bin/env bash
+
+username="Zhang Peng" ### 声明变量
+echo ${username} ### 输出变量的值
+unset username ### 删除变量
+echo ${username} ### 输出为空
+
+export HELLO="Hello World" ### 输出环境变量