shell 总结

1.[ expr ] isused to test whether expr is true or not, 'expr 运算'用来取值

如

if [ $# -eq 2 ]; then

echo "parameter 1 add parameter 2 is `expr $1 + $2`"

fi

如果运行时给参数sh ./wx/test.sh 1 2

输出结果parameter 1 add parameter 2 is 3

2. 各种流程语句的写法

2.1 if 语句

if [ $# -eq 0 ] ; then

exit 1

fi

if [ -f "test.sh" ]

then

echo "exist"

else

echo "not exist"

fi

else里面可以再嵌套if else

2.2 while语句

i=0

while [ $i -lt 3 ]

do

echo $i

i=`expr $i + 1`

done

输出结果

0

1

2

2.3 case语句

if [ -n $1 ];then

car=$1

case $car in

"bentian")

echo "bentian"

echo "show bentian";;

"baoma")

echo "baoma"

echo "show baoma";;

*)

echo "unknown";;

esac

fi

运行时给参数sh ./wx/test.sh bentian

输出结果

bentian

show bentian

给参数sh ./wx/test.sh ben

输出结果

unknown

2.4 for语句