Shell uses arrays

Define an array

Use parentheses to define an array , The definition can be initialized with elements , It can also be defined directly ：

array1=()
array2=(item1 item2 item3)

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Access array ：

The general format is ：

${arrayName[index]}

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for example ：

echo ${array2[1]}

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The subscript of the array is followed by C Language is the same from 0 At the beginning , So the output above is item2

You can also access all elements , The following two methods are equivalent ：

echo ${array2[*]}
echo ${array2[@]}

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Additional elements

array2[50]="abc"
array2[30]="def"

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Then let's see what the array looks like now ：

#!/bin/bash
array1=()
array2=(item1 item2 item3)
array2[50]="abc"
array2[30]="def"
echo ${array2[*]}
------------------------------
[email protected]:/usr/study$ ./array.sh
item1 item2 item3 def abc

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You can find , Subscripts do not need to be continuous when adding elements , When we output all the elements , If the element is null, it will be omitted automatically .

To obtain the length of the ：

len=${#array2[*]}

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perhaps

len=${#array2[@]}

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You can also get the length of the array elements ：

indexLen=${#array2[50]}

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there indexLen Refers to the number of characters of an element .