Array of Shell programming

Definition of 0x00 Array

The definition group of arrays has its place as a special data structure in any programming language, and of course the Bash shell is no exception. This article makes a small summary of the shell array. Here we only discuss the case of one-dimensional arrays, about multidimensional arrays (in fact, you have to use a one-dimensional array method to simulate), not involved. This includes copying, calculating, deleting, and replacing the array.

　　How arrays are defined:

1. Array[key]=value # arr[0]= "Hello" arr[1]= "World"

2. array= (value1 value2 ...) # arr= ("Hello" "world") note that there are spaces in front of parentheses

3. array= ([1]=value1 [2]=value2) # arr= ([0]= "Hello" [1]= "World")

Access to the 0x01 array

-Single access to elements in an array

${array[key]} # ${arr[1]}

-All elements in the array

Using the ${array name [subscript]} subscript is starting from 0 subscript is: * or @ Get the entire array contents

${array[* or @]} #${arr[*]}

-Calculate the length of the array

Use ${#数组名 [@ or *]} to get the array length

${#array [*]}

-Extraction of arrays

Directly through the ${array name [@ or *]: Start position: Length} Slice the original array, return is a string, the middle is separated by "space", so if you add "()", you will get the slice array

Arr= (1 2 3 4 5 6 7)

${arr[@]:0} # represents all elements

${ARR[@]:1} # Remove all elements after the first element

${arr[@]:0:2} # from 0 onwards fetch 2

-Deletion of array elements

Directly through: unset array [subscript] can clear the corresponding element, without subscript, clear the entire data.

Unset Arr[1]

-Substitution of array elements

${array name [@ or *]/find character/replace character} The operation does not change the contents of the original array

Arr= (1 2 3 4 5)

Echo ${ARR[@]/2/10} # result is 1 10 3 4 5

Arr= (${ARR[@]/2/10}) # Change the contents of the original array

Echo $arr # 1 10 3 4 5

Array of Shell programming