The Linux Shell Array uses

Ubuntu12.04 TLS 64bit, bash 4.2.25

First, the definition

An array is a collection of some data, divided into two types

(1) ordinary arrays, only integers can be used as indexes

(2) Associative array , can use string as index, Bash 4.0 start support, legacy version does not support

Second, some operations of the array

(1) Definition and assignment of arrays

< normal array >

"1" Definition

Array name = ()

"2" Value assignment

1. Array name = (elem1 elem2 elem3 ...)

Each element is separated by a space

2. Array name [0] = "test1"

array name [1] = "Test2"

......

< associative arrays >

"1" Definition

Declare-a array Name

"2" Value assignment

1. Array name = ([index1] = val1 [Index2] = Val2 ...)

2. Array name [INDEX1] = Val1

Array name [INDEX2] = Val2

......

(2) To find the length of the array

${#数组名 [*]} or {#数组名 [@]}

(3) Get an array of indexed elements

${array name [index value]}

(4) Get all elements of an array

${array name [*]} or ${array name [@]}

(5) Substitution of array elements

${array name [*]/find character/substitution character} or ${array name [@]/find character/replace character}

Replace does not change the original array, to modify the original array, you need to re-assign the value of the arrays

(6) Deleting an array element

unset array name #删除整个数组 unset array name [index value] #删除指定的元素

(7) Slicing of arrays

${array Name [*]: Start position: length} or ${array name [@]: Start position: Length}

A string separated by a space is returned after the slice, plus () the sub-array after the slice is obtained

Iii. examples

    #!/bin/bash                  #定义普通数组并进行赋值     comm_arr= (1 2 3 4 5)          comm_arr2= ()     comm_arr2[0]=6     comm_arr2[1]=7    comm_arr2[2]=8        # Get the length of the normal array     echo  "comm_arr1 len is ${#comm_arr [*]}"      echo  "comm_arr2 len is ${#comm_arr2 [@]}"           #获得普通数组的所有元素     echo  "comm_arr1 all elem is : ${comm_ Arr[*]} "    echo " comm_arr2 all elem is :${comm_arr2[@ "}"           #通过索引获得元素     echo  "comm_arr[4] =  ${COMM_ARR[4]} "    echo  "Comm_arr[2] = ${comm_arr2[2"} "    echo " comm_arr[ 100] = ${COMM_ARR[100]} "  #索引值不存在, but without error, the result is empty         # Substitution of elements in an ordinary array     echo  "3 IN COMM_ARR IS REPLACE 200 :  ${comm_arr[*]/3/200} "    echo " comm_arr is ${comm_arr[*]} " # The original array has not been modified     comm_arr2= (${COMM_ARR2[@]/7/9})    #替换原数组     echo   "7 IN COMM_ARR2 IS REPLACE 9 AND MODIFY COMM_ARR2"      echo  "comm_arr2 is ${comm_arr2[*]}"          #普通数组的切片     echo  "Splite comm_arr 1-3 is : ${comm_arr[*]:1:3 } "    comm_arr_split= (${comm_arr[@]:2:3})   #获得从第三个位置子开始3个元素的子数组      echo  "Sub arr : len = ${#comm_arr_split [*]} , elems is : ${comm_arr_split[@]} "          #普通数组的删除     echo  "Del before,  comm_arr is ${comm_arr[*]} "    echo " Del a elem "     unset comm_arr[0]  #删除某个元素     echo  "del after,  Comm_arr is ${comm_arr[*]} "        echo " Del all  arr "    unset comm_arr  #删除整个数组     echo " del  After, comm_arr is ${comm_arr[*]} "  #为空               #定义关联数组并赋值     declare -A link_arr     link_arr[' apple ']= ' 10$ '     link_arr[orange]= ' 100Y '          declare -a&nbsP;link_arr2    link_arr2= ([age]=20 [name]=zhangsan [sex]=m)           #获得关联数组的长度     echo  "link arr len: ${# Link_arr[*]} "    echo " link arr2 len: ${#link_arr2 [@]} "          #通过索引获得元素     echo  "Link arr index=apple ,  elem is ${link_arr[' apple '} '     echo  ' link arr2 index= Name, elem is ${link_arr2[name]} "    echo " link arr index= Name not exist, but no error, ${link_arr[name]} "  #虽然没有这个索引, but no error, just empty result          #输出关联数组中所有元素     echo  "Apple is  ${link_arr[*]} "    echo " link_arr2 is ${link_arr2[@ "}"         &nbSP; #关联数组中的替换     echo  "Link arr2 zhangsan is replace lisi,  ${link_arr2[*]/zhangsan/lisi} "  #原数组没有修改     echo " Link arr2 is  ${link_arr2[*]} "     #link_arr2 = (${link_arr2[*]/zhangsan/lisi})   #报错, associative array must use subscript      #echo   "link arr2 is ${link_arr2[*]}"      #echo   "Link arr2 name=${link_arr2[name]}"          #关联数组的切片     echo  "Link arr2 age-name: ${link_arr2[*]:name:2}"           #关联数组的删除     echo  "del before link  Arr2 is ${link_arr2[*]} "    unset link_arr2[age]     echo  "" del after link arr2 is ${link_arr2[*]}         unset link_arr    echo  "del all arr ${link_arr[*]}" 

Results:

COMM_ARR1 Len is 5
COMM_ARR2 Len is 3
COMM_ARR1 all Elem is:1 2 3 4 5
COMM_ARR2 all Elem Is:6 7 8
COMM_ARR[4] = 5
COMM_ARR[2] = 8
COMM_ARR[100] =
3 in Comm_arr is replace 200:1 2 200 4 5
Comm_arr is 1 2 3 4 5
7 in COMM_ARR2 is replace 9 and modify COMM_ARR2
COMM_ARR2 is 6 9 8
Splite Comm_arr 1-3 is:2 3 4
Sub Arr:len = 3, Elems is:3 4 5
Del before, Comm_arr is 1 2 3 4 5
Del a Elem
Del after, Comm_arr is 2 3 4 5
del all arr
Del after, Comm_arr is
Link arr Len:2
Link ARR2 Len:3
Link arr index=apple, Elem is 10$
Link arr2 index=name, Elem is Zhangsan
Link arr index=name not exist, but no error,
Apple is 100Y 10$
LINK_ARR2 is Zhangsan m
Link arr2 Zhangsan is replace Lisi, Lisi m
Link arr2 is Zhangsan m
Link ARR2 Age-name:zhangsan 20
Del before link arr2 is Zhangsan m
Del after link arr2 is Zhangsan m
del all arr

This article is from the "Snow Dancer" blog, please be sure to keep this source http://happytree007.blog.51cto.com/6335296/1711586

The Linux Shell Array uses