SHLL Foundation, the original script is not difficult!

------A small calculator-----

#!/bin/bash
#this

Read-p "Please enter the first integer:" One
Read-p "Please enter the second integer:" Two
Read-p "Please enter operator:" TH
echo "$ONE $th$two=$ (($ONE $TH $TWO)"

---------an If single branch statement-----

#!/bin/bash
#this

Read-p "Input directory:" DIR
if [!-D $DIR]
Then Mkdir-p $DIR
Fi

echo "Done"

---------an If double-spoke statement---

#!/bin/bash
#this

PING-C1-I0.1-W1 $

If [$?-eq 0]
Then echo "Are up!"
else echo "is down!"
Fi

=================if Nesting ================
#！ /bin/bash
#
Read-p "Please enter your score:" A
If [$A-le 10]
Then
echo "Congratulations to the finals"
Read-p "Please enter gender (boy/girl):" Sex
if [$SEX = boy]
Then
echo "Into the men's group"
Else
echo "Into the women's group"
Fi
Else
Echo, "I'm sorry you were eliminated."
Fi

-------The following is the case statement----------

#!/bin/bash
#this
Export LC_ALL=C//Case Sensitive

Read-p "Please enter the character:" KEY

Case $KEY in

    [A-Z] )            echo "您输入的$KEY是大写字母。"    ;;    [a-z] )            echo "您输入的$KEY是小写字母。"    ;;    [0-9] )            echo "您输入的$KEY是数字。"    ;;    ,)            echo "您输入的是$KEY。"    ;;    "#")            echo "您输入的是$KEY。"    ;;    *)            echo "您输入的是其它字符。"    ;;

Esac

-----------------The following is a function------------------
#!/bin/bash
Sum () {
Read-p "Please enter the first integer:" NUM1
Read-p "Please enter a second integer:" NUM2
echo "The two numbers you entered are: $NUM 1 and $num2. "
sum=$ (($NUM 1+ $NUM 2))
echo "Two number of the and is: $SUM"
#return $ (($NUM 1+ $NUM 2))//using the return value method, the maximum can not be greater than 255
}
Sum
#echo "Two number of the and is: $?"

---------The following is a for loop----------------

For IP in 192.168.80. {5..183}
Do
PING-C1-I0.2-W1 $IP &>/dev/null
If [$?-eq 0]
Then echo "$IP is up!"
else echo "$IP is down!"
Fi
Done

----------The following is an example------------

#!/bin/bash
#

For USER in test{1..10}
Do
Useradd $USER
echo "${USER}ABC" | passwd--stdin $USER &>/dev/null
Done

cat/etc/passwd

-----------Here is the while example-----------

#!/bin/bash
#

I=1
Pre=test

While [$i-le 10]
Do
Useradd $PRE $i
echo "123" | passwd--stdin $PRE $i &>/dev/null
Let i++
Done
Echo $i
cat/etc/passwd

===================until Loop Statement =====================
# #条件不满足循环, stop when you are satisfied # #
Calculates the value of a 1~50
[Email protected] ~]# VI sum1to50_until_v1.sh
#!/bin/bash
# #filename: sum1to50_until_v1.sh
I=0;s=0
Until [$i-eq 50]
Do
Let "i= $i +1", let "s= $s + $i"
Done
Echo ' sum (1..50) = ' $s

=========================== Double Cycle ==================
#!/bin/bash
#
H=1
While [$H-le 10]
Do
L=1
While [$L-le $H]
Do
Echo-n "$L"
Let l++
Done
echo ""
Let h++

Done
Final output:
1
12
123
1234
12345
123456
1234567
12345678
123456789
12345678910

===================shell Array ========================

Shell Array
1. Get the array length
[Email protected] ~]# arr_number= (1 2 3 4 5);
[Email protected] ~]# arr_length=${#arr_number [*]}
[Email protected] ~]# echo $arr _length
5

2. Reading a subscript assignment
[[email protected] ~]# arr_index2=${arr_number[2]}
[Email protected] ~]# echo $arr _index2
3

3. Array traversal
[[email protected] ~]# for V in ${arr_number[@]}

Do
Echo $v
Done
1
2
3
4
5

SHLL Foundation, the original script is not difficult!