BASH-TRANSLATION-EXAMPLES.md

Examples of translation from Bash syntax to POSIX-arrays syntax

Indexed arrays

Declaring an array, assigning and adding values, unsetting elements

Bash: declare test_arr=(a b c)

POSIX-arrays:declare_i_arr test_arr a b c

Bash: test_arr[100]="this is a test"

POSIX-arrays:set_i_arr_el test_arr 100 "this is a test"

Bash: test_arr+=("this is another test")

POSIX-arrays:add_i_arr_el test_arr "this is another test"

Getting values and indices

Bash: echo "value for index 100 is $test_arr[100]"

POSIX-arrays: get_i_arr_val test_arr 100 value; echo "value for index 100 is $value"

Bash: echo "all values of test_arr are '${test_arr[*]}'"

POSIX-arrays: get_i_arr_values test_arr values; echo "all values of test_arr are '$values'"

POSIX-arrays (to get a sorted list): get_i_arr_values -s test_arr values; echo "sorted values of test_arr are '$values'"

Bash: echo "all indices of test_arr are '${!test_arr[*]}'"

POSIX-arrays: get_i_arr_indices test_arr indices; echo "all indices of test_arr are '$indices'"

POSIX-arrays (to get a sorted list): get_i_arr_indices -s test_arr indices; echo "sorted indices of test_arr are '$indices'"

Bash: echo "test_arr has '${#test_arr[@]}' elements"

POSIX-arrays: get_i_arr_el_cnt test_arr el_cnt; echo "test_arr has '$el_cnt' elements"

Bash: indices=( "${!test_arr[@]}" ); echo "max index of test_arr is '${indices[-1]}'"

POSIX-arrays: get_i_arr_max_index test_arr maxindex; echo "max index of test_arr is '$maxindex'"

Bash: echo "last value of test_arr is '${test_arr$[-1]}'"

POSIX-arrays: get_i_arr_last_val test_arr lastval; echo "last value of test_arr is '$lastval'"

Unsetting arrays

Bash: declare temp_arr=("this array will be destroyed"); unset temp_arr

POSIX-arrays: declare_i_arr temp_arr "this array will be destroyed"; unset_i_arr temp_arr

Working with loops

Bash:

declare test_arr=("no_whitespaces_value1" "no_whitespaces_value2")
for value in ${test_arr[@]}; do
    echo "$value"
done

POSIX-arrays:

declare_i_arr test_arr "no_whitespaces_value1" "no_whitespaces_value2"
get_i_arr_values test_arr values
for value in $values; do
    echo "$value"
done

Bash:

declare test_arr=("i_don't_have_whitespaces" "i have whitespaces")
for value in ${test_arr[@]}; do
    echo "$value"
done

POSIX-arrays (here we need to loop over indices rather than over values, to avoid whitespace issues):

declare_i_arr test_arr "i_don't_have_whitespaces" "i have whitespaces"
get_i_arr_indices test_arr indices
for index in $indices; do
    get_i_arr_val "$index" value
    echo "$value"
done

Bash:

for index in ${!test_arr[@]}; do
    echo "$index"
done

POSIX-arrays:

get_i_arr_indices test_arr indices
for index in $indices; do
    echo "$index"
done

Associative arrays

Declaring an array, assigning and adding values, unsetting elements

Bash: declare -A test_arr=([key1]=val1 [key2]=val2)

POSIX-arrays: declare-a-arr test_arr key1=val1 key2=val2

Bash: test_arr[key]="test value"

POSIX-arrays: set_a_arr_el test_arr key="test value"

Bash: unset test_arr[key]

POSIX-arrays: unset_a_arr_el test_arr key

Getting values, keys and parameters

Bash: echo "value for 'key': '${test_arr[key]}'"

POSIX-arrays: get_a_arr_val test_arr value; echo "value for 'key': '$value'"

Bash: echo "all values of test_arr are '${test_arr[*]}'"

POSIX-arrays: get_a_arr_values test_arr values; echo "all values of test_arr are '$values'"

POSIX-arrays (to get a sorted by key list): get_a_arr_values -s test_arr values; echo "sorted by key values of test_arr are '$values'"

Bash: echo "all keys of test_arr are '${!test_arr[*]}'"

POSIX-arrays: get_a_arr_keys test_arr keys; echo "all keys of test_arr are '$keys'"

POSIX-arrays (to get a sorted list): get_a_arr_keys -s test_arr keys; echo "sorted keys of test_arr are '$keys'"

Bash: echo "test_arr has '${#test_arr[@]}' elements"

POSIX-arrays: get_a_arr_el_cnt test_arr el_cnt; echo "test_arr has '$el_cnt' elements"

Unsetting arrays

Bash: unset temp_arr

POSIX-arrays: unset_i_arr temp_arr

Working with loops

Bash:

for value in ${test_arr[@]}; do
    echo "$value"
done

POSIX-arrays:

get_a_arr_values test_arr values
for value in $values; do
    echo "$value"
done

Bash:

for key in ${!test_arr[@]}; do
    echo "$key"
done

POSIX-arrays:

get_a_arr_keys test_arr keys
for key in $keys; do
    echo "$key"
done