questions

1：

#!/bin/bash
# auth: xiluhua
# date: 2017-01-15
 
while true
do 
        read -p 'please input a film: ' film
        if [ -z $film ]
        then
                echo > /dev/null
        else
                if [ $film = 'q' ]
                then 
                        exit
                fi
 
                if [ $film = 'ironman' ]
                then
                        echo $film' is a good film!'
                        exit 0;
                else
                        echo 'this film is not good enough'
                fi
        fi
done

解决方案：$film改成"$film"

#!/bin/bash
# auth: xiluhua
# date: 2017-01-15
 
while true
do 
    read -p 'please input a film: ' film
        echo $film
    if [ -z "$film" ]
    then
        echo > /dev/null
    else
        if [ "$film" = 'q' ]
        then 
            exit
        fi  
 
        if [ "$film" = 'iron man' ]
        then
            echo "$film"' is a good film!'
            exit 0;
        else
            echo 'this film is not good enough'
        fi  
    fi  
done

2. history -d 47 5

参数 5 没有起作用

3. 如何给less,cat命令设定tab缩进为4个空格？

4. yum list 结果的第三列枚举含义

root@vm-xiluhua /mnt # yum -q list | awk '{print $3}'| sort -u
 
@anaconda
@base
installed
local
@updates