Linux Chapter2

Shell Programming
重定向:>,<
追加:>>
拉机桶/dev/null
管道:|
用来把进程连接在一起,
脚本程序
#!/bin/sh
myvar="HI"
echo ENTER SOMETHING
read myvar
echo \$myvar is now $myvar
exit 0
单引号不替换变量,双引号替换

测试用[]
#!/bin/sh
echo "is it morning,enter yes or no"
read anser
if [ "$anser" = "yes" ];then
echo GOOD MORNING
elif [ "$anser" = "no" ];then
echo Good afternoon
else
echo please enter yes or no
exit 1
fi
exit 0

#!/bin/sh
for file in $(ls *.c);do
echo $file
done
exit 0