How to understand linux shell array

This article introduces you how to understand linux shell array, the content is very detailed, interested friends can refer to reference, I hope to help you.

To introduce you to the linux shell array related knowledge, and provides sufficient examples for reference.

Declare an array:

declare -a array

(In fact, you don't have to declare it, you can assign it directly to the variable in array mode, BASH knows that it is an array)

Array assignment:

(1) array=(var1 var2 var3 … varN)

(2) array=([0]=var1 [1]=var2 [2]=var3 … [n]=varN)

(3) array[0]=var1

arrya[1]=var2

…

array[n]=varN

Counting the number of array elements:

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

BASH's special parameters @ and * both mean "extended positional parameters, starting with 1", but the form is slightly different, but it seems to be universal when used in arrays.

Reference array:

The copy code is as follows:

echo ${array[n]}

Traverse array:

The copy code is as follows:

filename=(ls)

for var in ${filename[@]};do

echo $var

done

Here are some examples of shell arrays.

1. Read n strings from "standard input", and save the strings entered each time in array.

The copy code is as follows:

#!/ bin/bash

i=0

n=5

while [ "$i" -lt $n ] ; do

echo "Please input strings …expr $i + 1"

read array[i]b=i]b=i]b={array[KaTeX parse error: Expected 'EOF', got '}' at position 3: i]}̲ echo "b"

i=expr $i + 1

done

2. Put the letters in the string into the array one by one and output them to "standard output".

The copy code is as follows:

#!/ bin/bash

chars='abcdefghijklmnopqrstuvwxyz'

for (( i=0; i