shell脚本小练习

提示用户输入一个数，判断这个数是否是你想要的。想要的就打出 yes，否则就是no。

#!/bin/bash

numWanted=8
read -p "please input a number:" num
if [ -n "$num" -a "$num" -gt "$numWanted" ]; then
echo "yes"
else
echo "no"
fi

#其他方法
[ "$num" ] && [ "$num" -gt "$numWanted" ] && echo "yes" && exit 0
echo "no"
exit 1

提示用户输入一个文件/目录，判断这个文件具有哪些属性？
#!/bin/bash

read -p "please input a filename: " filename
if [ -z "$filename" ]; then
echo "you need to input a filename"
exit 1
fi

#检测文件是否存在
test ! -e "$filename" && echo "$filename doesn't exist" && exit 1

#判断文件类型
if [ -f "$filename" ]; then
filetype="regular file"
elif [ -d "$filename" ]; then
filetype="directory"
else
echo "$filename is neither a regular file nor a directory"
exit 1
fi

#判断文件读写执行权限
[ -r "$filename" ] && perm="readable"
[ -w "$filename" ] && perm="$perm writable"
[ -x "$filename" ] && perm="$perm executable"

#输出
echo -e "\nThe filename: $filename is a $filetype"
echo "And the permissions are: $perm"



写一个输入新的文件名，就自动创建C源文件的脚本程序
文件一：源文件模板ctemplate
#include

int main(int argc,char *argv[])
{

return 0;
}

文件二：脚本文件createC.sh
#!/bin/bash

#判断是否提供了一个文件名
if [ "$#" -ne 1 ]; then
echo "you need to input one "
exit 1
fi
#判断该文件是否已经存在
if [ -e "$1" ]; then
echo "filename $1 has existed."
exit 1
fi
#创建带有main函数的源文件
if ! cp /root/shtest/ctemplate $1 2>/dev/null
then
echo "create file error"
exit 1
fi
vim $1

提示用户输入一字符串，字符串必须为 “case”或者”esac” ,并打印出来。如果输入的是其他字符串打印出错消息。
#!/bin/bash

read -p "please input string 'case' or 'esac': " str

test -z "$str" && echo "you need to input a string" && exit 1

case "$str" in
"case")
echo "you input case"
;;
"esac")
echo "you input esac"
;;
*)
echo "input error!"
;;
esac


系统上面的各种账号都是写在/etc/passwd 内的第一个字段，你能不能通过命令cut找出每个账号的名称，用命令id、finger 输出他们的相关信息呢？
#!/bin/bash

users=$(cut -d ':' -f 1 /etc/passwd)

for username in $users
do
id $username
finger $username
done



若想让用户输入一个目录名， 然后我找出该目录内的每个文件的读写执行权限，该如何做？
#!/bin/bash

read -p "please input a directory: " dirname

if [ -z $dirname -o ! -d $dirname ]; then
echo "input error or directory $dirname not found"
exit 1
fi

files=$(ls $dirname)
for filename in $files
do
perm=""
test -r $filename && perm="readable"
test -w $filename && perm="$perm writable"
test -x $filename && perm="$perm executable

"
echo "$filename: $perm"
done

让用户输入一个数字，程序可以由 1+2+3... 一直累加到用户输入的数字为止。
#!/bin/bash

read -p "please input a number that is bigger than 0: " num

if [ $num -lt 1 ]; then
echo "you need to input a number bigger than 0"
exit 1
fi
sum=0
for ((i=1;i<=$num;i++))
do
sum=$(($sum+$i))
done

echo "your number is $num, sum is $sum"