Introduction
A shell variable is capable enough to hold a single value. This type of variables are called scalar variables. Shell supports a different type of variable called an array variable that can hold multiple values at the same time. Arrays provide a method of grouping a set of variables. Instead of creating a new name for each variable that is required, you can use a single array variable that stores all the other variables. All the naming rules discussed for Shell Variables would be applicable while naming arrays.
Defining Array Values
The difference between an array variable and a scalar variable can be explained as follows. Say that you are trying to represent the names of various students as a set of variables. Each of the individual variables is a scalar variable as follows −
- NAME01="Zara"
- NAME02="Qadir"
- NAME03="Mahnaz"
- NAME04="Ayan"
- NAME05="Daisy"
- NAME[0]="Zara"
- NAME[1]="Qadir"
- NAME[2]="Mahnaz"
- NAME[3]="Ayan"
- NAME[4]="Daisy"
- set -A array_name value1 value2 ... valuen
- array_name=(value1 ... valuen)
After you have set any array variable, you access it as follows:
- ${array_name[index]}
- test.sh
- #!/bin/sh
- NAME[0]="Zara"
- NAME[1]="Qadir"
- NAME[2]="Mahnaz"
- NAME[3]="Ayan"
- NAME[4]="Daisy"
- echo "First Index: ${NAME[0]}"
- echo "Second Index: ${NAME[1]}"
You can access all the items in an array in one of the following ways:
- ${array_name[*]}
- ${array_name[@]}
- test2.sh
- #!/bin/sh
- NAME[0]="Zara"
- NAME[1]="Qadir"
- NAME[2]="Mahnaz"
- NAME[3]="Ayan"
- NAME[4]="Daisy"
- echo "First Method: ${NAME[*]}"
- echo "Second Method: ${NAME[@]}"
Supplement
* Bash For Loop Array: Iterate Through Array Values
* [Linux 常見問題] Shell - Does linux shell support list data structure?
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