5.1.3 Arrays

(1) Creating arrays

The following explains how to create an array.

• If you create multiple elements at one time (using the set command)

  One-dimensional array

  set -A array-name value value ...
  set +A array-name value value ...

  Two-dimensional array

  set -D array-name { value value ... } { value value ... } ... 
  set +D array-name { value value ... } { value value ... } ...

  In one-dimensional array, specify one or more half-width space as a delimiter for the array name to be created and elements registered for the array.

  set ∆-A∆array name∆value∆value∆...

  Specify one or more half-width space for ∆.

  Usage examples (one-dimensional array)

  set -A abc 1 2 3
  echo ${abc[1]}

  -->2 is output to the standard output.

  In two-dimensional array, specify one or more half-width space as a delimiter for the array name to be created, "{" and "}" enclosing elements of array and elements registered for the array.

  set∆-D∆array-name∆{∆value∆value∆...∆}∆{∆value∆value∆...∆}∆...

  Specify one or more half-width space for ∆.

  Usage examples (two-dimensional array)

  set -D abc { 1 2 3 } { 4 5 6 }
  echo ${abc[1][1]}

  -->5 is output to the standard output.

  This method can create multiple elements at a time. For details about the set -A command and set -D command, see 9.3 Standard shell commands > set command (sets shell option, creates an array or displays variable values).

• If you create one element

  One-dimensional array

  array-name[element-number]=value

  Two-dimensional array

  array-name[element-number-1][element-number-2]=value

  Usage examples (one-dimensional array)

  abc[0]=1
  abc[1]=2
  abc[2]=3
  echo ${abc[1]}

  -->2 is output to the standard output.

  Usage examples (two-dimensional array)

  abc[0][0]=1
  abc[0][1]=2
  abc[0][2]=3
  echo ${abc[0][1]}

  -->2 is output to the standard output.

  This method creates one element at a time. To create multiple elements, perform the step as many times as there are elements to be created. In addition, an array with element number 0 (abc[0] or abc[0][0]) is handled in the same manner as variables.

• If you multiple elements at the same time (without using the set command)

  One-dimensional array

  array-name=(value value ...)

  Two-dimensional array

  array-name []=({ value value ... } { value value ... } ...)

  In one-dimensional array, specify one or more half-width space as a delimiter for the array name to be created.

  array-name=(value∆value∆...)

  Specify one or more half-width space for ∆.

  Usage examples (one-dimensional array)

  abc=(1 2 3)
  echo ${abc[1]}

  -->2 is output to the standard output.

  In two-dimensional array, specify one or more half-width space as a delimiter for the array name to be created, "{" and "}" enclosing elements and elements registered for the array.

  array-name[]=({∆value∆value∆...∆}∆{∆value∆value∆...∆}∆...

  Specify one or more half-width space for ∆.

  Usage examples (two-dimensional array)

  abc[]=({ 1 2 3 } { 4 5 6 })
  echo ${abc[1][2]}

  -> 6 is output to the standard output.

  This method can create multiple elements at a time. For details about creation method, see (2) Creating arrays by using array-name=(value value ...).

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(2) Creating arrays by using array-name=(value value ...)

The one-dimensional array that is defined in the syntax of "syntax name=(value value ...)" is registered in the syntax of "set -A array-name value value ...".

The two-dimensional array that is defined in the syntax of "array-name[]=({ value value ... } { value value ... } ...)" is registered in the syntax of "set -D syntax-name { value value ... } { value value ... }".

Execution of the "set command" is output to the JOBLOG instead of the syntax of "array-name=(value value ...)" and "array-name []=({ valuevalue ... } { value value ... } ...)".

How to manage the array element is the same as other arrays even if the array is created in the syntax of "array-name=(value value ...)". For example, the one-dimensional array is the same array as the array that is created in the format of "set -A ARRAY x1 x2 x3 x4 x5".

Array elements for an array defined as ARRAY=(x1 x2 x3 x4 x5)

ARRAY[0]=x1
ARRAY[1]=x2
ARRAY[2]=x3
ARRAY[3]=x4
ARRAY[4]=x5

#:

n indicates two-dimensional array element.

For the two-dimensional array, how to manage the array element is the same as that of the array that is created by using the set-D command if the array is created in the syntax of "array-name[]=({ value value ... } { valuevalue ... } ...)". For example, the two-dimensional array is the same array as the array that is created in the format of "set -D ARRAY { x1 x2 x3 } { x4 x5 x6 }".

Element of array if defined as ARRAY[]=({ x1 x2 x3 } { x4 x5 x6 })

ARRAY[0][0]=x1
ARRAY[0][1]=x2
ARRAY[0][2]=x3
ARRAY[1][0]=x4
ARRAY[1][1]=x5
ARRAY[1][2]=x6

#1:

n indicates two-dimensional array element.

#2:

m indicates two-dimensional array element.

Therefore, output to JOBLOG, coverage collection, and output of the xtrace shell option all have the same result as when the set command is used to define arrays.

If array-name=() is defined, a shell variable whose name is array-name and value is the null string is created. This is the same as when array-name= is defined.

A=a
B=b
C=c
MA=' a b c' #
MB=d

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(3) Referencing the values of arrays

The following explains how to reference the values in an array.

• If you reference a value of one element of one-dimensional array

  ${array-name[element-number]}

  Example:

  set -A abc 1 2 3

  echo ${abc[1]}

  --> 2 is output to the standard output.

• If you reference a value of one element of two-dimensional array

  ${array-name[element-number-1][element-number-2]}

  Usage examples

  set -D abc { 1 2 3 } { 4 5 6 }
  echo ${abc[1][2]}

  -->6 is output to the standard output.

  In two-dimensional array, the same as for a one-dimensional array, if you specify either @ or * for the array element number, all elements of values defined for the array are referenced. Unlike one-dimensional array, there are 2 specified array element numbers so that you can specify each symbol and array number. If you specify either @ or *, all array elements are not specified for reference. The reference range if you specify ${array[n][m]} is as follows:

  Table 5‒4: Reference range if ${array[n][m]} is specified

  n	m
  	Not specified	[]	[m]	[@]	[*]
  []	Value of array[0][0]	Value of array[0][0]	Value of array[0][m]	All arrays	All arrays
  [n]	Value of array[n][0]	Value of array[n][0]	Value of array[n][m]	All of the n line	All of the n line
  [@]	All arrays	All arrays	All of the m column	All arrays	All arrays
  [*]	All arrays	All arrays	All of the m column	All arrays	All arrays

  If you specify @ and *, the symbol specified for the element number 1 is prioritized.

  If you specify array[@][*], array[@][@] is considered to be set. If you specify array[*][@], array[*][*] is considered to be set.

• If you reference a value of element of array

  • If you reference a value of element of one-dimensional array

    Reference method 1

    ${array-name[*]}

    Usage examples

    set -A abc 1 2 3
    echo ${abc[*]}

    -->1 2 3 is output to the standard output.

    Reference method 2

    ${array-name[@]}

    Usage examples

    set -A abc 1 2 3
    echo ${abc[@]}

    -->1 2 3 is output to the standard output.

    Reference method 3

    "${array-name[*]}"

    Note: When this method is used, each value is separated by the value of the IFS shell variable.

    Usage examples

    set -A abc 1 2 3
    IFS=:
    echo "${abc[*]}"

    -->1 2 3 is output to the standard output.

    Reference method 4

    "${array-name[@]}"

    Usage examples

    set -A abc 1 2 3
    echo "${abc[@]}"

    -->1 2 3 is output to the standard output.

  • If you reference a value of element of two-dimensional array

    Reference method 1

    ${array-name[*][*]}

    Usage examples

    set -D abc { 1 2 3 } { 4 5 6 }
    echo ${abc[*][*]}

    -->1 2 3 4 5 6 is output to the standard output.

    Reference method 2

    ${array-name[@][@]}

    Usage examples

    set -D abc { 1 2 3 } { 4 5 6 }
    echo ${abc[@][@]}

    -->1 2 3 4 5 6 is output to the standard output.

    Reference method 3

    ${array-name[1][*]}

    Usage examples

    set -D abc { 1 2 3 } { 4 5 6 }
    echo ${abc[1][*]}

    -->4 5 6 is output to the standard output.

    Reference method 4

    ${array-name[1][@]}

    Usage examples

    set -D abc { 1 2 3 } { 4 5 6 }
    echo ${abc[1][@]}

    -->4 5 6 is output to the standard output.

    Reference method 5

    ${array-name[*][1]}

    Usage examples

    set -D abc { 1 2 3 } { 4 5 6 }
    echo ${abc[*][1]}

    -->2 5 is output to the standard output.

    Reference method 6

    ${array-name[@][1]}

    Usage examples

    set -D abc { 1 2 3 } { 4 5 6 }
    echo ${abc[@][1]}

    -->2 5 is output to the standard output.

    For other specification combinations, see Table 5‒4: Reference range if ${array[n][m]} is specified.

The following shows an example of referencing the values of an array:

Contents of job definition script

set -A myArray a01 a02 a03     # Define myArray as an array
for myElement in ${myArray[*]} # Expand all elements of myArray to wordlists in the for statement
do
  echo $myElement
done

Results output to the standard output

a01
a02
a03

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(4) Regarding the necessary amount of memory for securing a large amount of an element of the array

You can create a maximum of 65,536x64 elements of array in a two-dimensional array.

The maximum number of elements of array may not be ensured depending on the amount of available memory that is granted to the process that creates the two-dimensional array.

The formula for estimating the memory amount that is required for creating a two-dimensional array is as follows:

(324+x) × y
x: Average array element data (specified by rounding up the value in units of multiples of 8)
y: Maximum number of array elements to be created (1 to 65,536×64).

Confirm that the total of the aforementioned necessary memory amount and required amount of memory that is used by other syntax does not exceed the memory amount that is available in the process.

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