#! /bin/bash

if [ $# -ne 1 ]
then
    echo arguments not valid
    exit 1
fi

if [ ! -e "$1" ]
then
    echo not exist
    exit 2
fi

if [ -f "$1" ]
then
    echo regular file
fi


if [ -d "$1" ]
then
    echo directory
fi

if [ -r "$1" ]
then
    echo readable
fi

if [ -w "$1" ]
then
    echo writable
fi

if [ -x "$1" ]
then
    echo executable
fi

在shell函数中，return的作用是表达程序是否正常结束，return 0代表程序正常结束，否则表示异常结束；而echo的作用是返回程序计算结果的值

1. top列出所有进程，M 按内存排序
2. ps aux 返回所有打开的进程。

添加执行权限： chmod + x *.sh
可以 bash *.sh 执行 或者sh *.sh
注意开多个pane时，要把vim 编辑的文件保存退出，再提交测试。否则会有.swap文件。

#! /bin/bash

dir0=/home/acs/homework/lesson_1/homework_0
dir1=/home/acs/homework/lesson_1/homework_1
dir2=/home/acs/homework/lesson_1/homework_2
dir3=/home/acs/homework/lesson_1/homework_3
dir4=/home/acs/homework/lesson_1/homework_4
dir5=/home/acs/homework/lesson_1/homework_5
dir6=/home/acs/homework/lesson_1/homework_6
dir7=/home/acs/homework/lesson_1/homework_7
dir8=/home/acs/homework/lesson_1/homework_8
dir9=/home/acs/homework/lesson_1/homework_9

# homework 1 create

# ***homework_0***
for i in dir_a dir_b dir_c
do
    mkdir ${dir0}/$i
done

# ***homework_1***
bf0=.txt
bf1=.bak

for i in a b c
do

    cp ${dir1}/${i}${bf0} ${dir1}/${i}${bf0}${bf1}
done

# ***homework_2***
bf2=_new
for i in a b c
do

    mv ${dir2}/${i}${bf0} ${dir2}/${i}${bf2}${bf0}
done

# ***homework_3***

for i in a b c
do
    mv ${dir3}/dir_a/${i}${bf0} ${dir3}/dir_b/
done


# ***homework_4***

rm ${dir4}/*.txt

# ***homework_5***

for i in a b c
do
    rm ${dir5}/dir_${i} -r
    # rm ${dir5}/* -r
done

# ***homework_6***


mv ${dir6}/task.txt "${dir6}/done.txt"

mkdir ${dir6}/dir_a

mv "${dir6}/done.txt" ${dir6}/dir_a/

# ***homework_7***

for i in 0 1 2
do
    mkdir ${dir7}/dir_${i}

    for j in a b c
    do
        cp ${dir7}/${j}.txt ${dir7}/dir_${i}/${j}${i}.txt
    done

done



# ***homework_8***

rm ${dir8}/dir_a/a.txt

mv ${dir8}/dir_b/b.txt ${dir8}/dir_b/b_new.txt

cp  ${dir8}/dir_c/c.txt ${dir8}/dir_c/c.txt.bak

# ***homework_9***

rm ${dir9}/*.txt


# homework 1 test

//这里填你的代码^^
//注意代码要放在两组三个点之间，才可以正确显示代码高亮哦~

//这里填你的代码^^
//注意代码要放在两组三个点之间，才可以正确显示代码高亮哦~

//这里填你的代码^^
//注意代码要放在两组三个点之间，才可以正确显示代码高亮哦~

//这里填你的代码^^
//注意代码要放在两组三个点之间，才可以正确显示代码高亮哦~

//这里填你的代码^^
//注意代码要放在两组三个点之间，才可以正确显示代码高亮哦~