转载－shell函数应用实例介绍-优快云博客

本文介绍了一个使用Shell脚本实现的简易数据库管理系统。该系统包括添加员工信息、删除信息等功能，并通过循环和条件判断确保数据输入正确。此外，还演示了如何通过内部函数对数据进行排序。

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原文地址：http://blog.chinaunix.net/u/4206/showart.php?id=654250

代码:
$cat dbfunctions
addon () {                # 定义函数addon,他的功能是把新的信息加入datafile
while true
do
      echo "Adding information "
      echo "Type the full name of employee "
      read name
      echo "Type address for employee "
      read address
      echo "Type start date for employee (4/10/88 ) :"
      read startdate
      echo $name:$address:$startdate
      echo -n "Is this correct? "
      read ans
      case "$ans"  in
      [Yy]*)
         echo "Adding info..."
         echo $name:$address:$startdate>>datafile
         sort -u datafile -o datafile
         echo -n "Do you want to go back to the main menu? "
         read ans
         if [ $ans = Y -o $ans = y ]
         then
            return       # return命令把控制送回函数被调用时所在的调用程序
   else
            continue       # 把控制返回到while循环顶部
         fi
            ;;
      *)
         echo "Do you want to try again? "
         read answer
         case "$answer" in
            [Yy]*)
                  continue;;
            *)
                  exit;;
         esac
            ;;
      esac
done
}    # 结束函数定义

$cat mainprog
#!/bin/sh
script. name: mainprog
# This is the main script. that will call the function, addon

#datafile=$HOME/bourne/datafile
datafile=./datafile

.  dbfunctions  # dot命令把文件dbfunctions装入内存,

if [ ! -f $datafile ]
then
echo "`basename $datafile` does not exist" 1>&2
exit 1
fi
echo "Select one: "
cat <<EOF
[1] Add info
[2] Delete info
[3] Exit
EOF
read choice
case $choice in
1)  addon # 调用函数
      ;;
2)  delete  # 调用函数
      ;;
3)  update
      ;;
4)  echo Bye
      exit 0
      ;;
*)  echo Bad choice
      exit 2
      ;;
esac
echo Returned from function call
echo The name is $name
# Variable set in the function are known in this shell.

附:文件datafile
cat database
Ann Stephens          111 Main St, Boston, MA       4/10/88
TB Savage             222 B Ave, New York, NY       5/11/99