shell脚本练习

　练习一：写一个脚本
       1.设定变量FILE的值为/etc/passwd
       2.依次向/etc/passwd中的每个用户问好，并且说出对方的ID是什么
        形如：（提示：LINE=`wc -l /etc/passwd | cut -d" " -f1`)
         Hello,root，your UID is 0.
       3.统计一个有多少个用户

答案一：#!/bin/bash
           file="/etc/passwd"
           LINES=`wc -l $file | cut -d" " -f1`
           for I in `seq 1 $LINES`;do
           userid=`head -$I $file | tail -1 |cut -d: -f3`
           username=`head -$I $file | tail -1 |cut -d: -f1`
           echo "hello $username,your UID is $userid"
           done
           echo "there are $LINES users"

已掌握

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答案二：

#!/bin/bash
           file=/etc/passwd
           let num=0
           for I in `cat $file`;do
           username=`echo "$I" | cut -d: -f1`
           userid=`echo "$I" | cut -d: -f3`
           echo "Hello,$username,your UID is $userid"
           num=$[$num+1]
           done
           echo "there are $num users"

问题，I in `cat /etc/passwd`

echo "$I" | cut -d: -f1不能截取每一行，如何实现的？？

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练习二：写一个脚本
      1.切换工作目录至/var
      2.依次向/var目录中的每个文件或子目录问好，形如：
        （提示：for FILE in /var/*;或for FILE in `ls /var`;)
        Hello,log
      3.统计/var目录下共有多个文件，并显示出来
  答案：#!/bin/bash
         cd /var
         let num=0
         for I in `ls /var/*`;do
         echo "hello $I"
         num=$[$num+1]
         done
         echo "the number of files is $num"

问题同上

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shell脚本练习

原文：https://www.cnblogs.com/wenter2016/p/10120600.html