Array of shell script programming

Variable: Stores the memory space of a single element;

Array: A contiguous memory space that stores multiple elements;

Array name: The entire array has only one name;

Array index: numbering starting from 0;

Array name [index],

${array_name[index]}

Associative arrays:

Note: Bash-4 and later versions support custom index formats, not just 0,1,2, ... Number format;

Such arrays are called "associative arrays".

Declaring an array:

Declare-a NAME: declares an indexed array;

Declare-a NAME: declares an associative array;

How the elements in the array are assigned:

(1) Assign only one element at a time;

Array_name[index]=value

(2) An assignment of all elements at once;

Array_name= ("VAL1" "VAL2" "VAL3" ...)

(3) assigning only specific elements;

Array_name= ([0]= "VAL1" [3]= "VAL4" ...)

NOTE: Bash supports sparse-format arrays;

(4) Read-a Array_Name

Referencing an element in an array: ${array_name[index]}

Note: When referencing, only the array name is given, which refers to the element that is labeled 0;

The length of the array (the number of elements in the array):

${#ARRAY_NAME [*]}

${#ARRAY_NAME [@]}

Example: Generate 10 random numbers and find the maximum and minimum values;

#!/bin/bash#declare-a randdeclare-i max=0for i in {0..9}; Do rand[$i]= $RANDOM echo ${rand[$i]} [${rand[$i]}-gt $max] && max=${rand[$i]}doneecho "Max: $max"

Exercise: Write a script

Defines an array in which the elements in the array are all files that end with. Log in the/var/log directory, and the sum of the number of rows in the file whose subscript is even;

#!/bin/bash#declare-a filesfiles= (/var/log/*.log) declare-i lines=0for i in $ (seq 0 $[${#files [*]}-1]); do if [$[$i%2]-eq 0]; Then let lines+=$ (Wc-l ${files[$i]} | cut-d '-f1) Fidoneecho "lines: $lines."

To reference all elements in an array:

${array_name[*]}

${array_name[@]}

Array element slice: ${array_name[@]:offset:number}

Offset: The number of elements to pass;

Numbers: The number of elements to be taken out, and the amount of all elements after the offset is omitted;

To append an element to a non-sparse format array:

array_name[${#ARRAY_NAME [*]}]=

To delete an element in an array:

Unset Array[index]

Associative arrays:

Declare-a Array_Name

Array_name= ([index_name1]= "value1" [index_name2]= "value2" ...)

This article is from the "Wang Liming" blog, make sure to keep this source http://afterdawn.blog.51cto.com/7503144/1916071

Array of shell script programming