Split string into an array in Bash

arrays bash split
Lgn picture Lgn · May 14, 2012 · Viewed 946.8k times · Source

In a Bash script I would like to split a line into pieces and store them in an array.

The line:

Paris, France, Europe

I would like to have them in an array like this:

array[0] = Paris
array[1] = France
array[2] = Europe

I would like to use simple code, the command's speed doesn't matter. How can I do it?

Answer

Paused until further notice. picture Paused until further notice. · May 14, 2012 
IFS=', ' read -r -a array <<< "$string"

Note that the characters in $IFS are treated individually as separators so that in this case fields may be separated by either a comma or a space rather than the sequence of the two characters. Interestingly though, empty fields aren't created when comma-space appears in the input because the space is treated specially.

To access an individual element:

echo "${array[0]}"

To iterate over the elements:

for element in "${array[@]}"
do
    echo "$element"
done

To get both the index and the value:

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

The last example is useful because Bash arrays are sparse. In other words, you can delete an element or add an element and then the indices are not contiguous.

unset "array[1]"
array[42]=Earth

To get the number of elements in an array:

echo "${#array[@]}"

As mentioned above, arrays can be sparse so you shouldn't use the length to get the last element. Here's how you can in Bash 4.2 and later:

echo "${array[-1]}"

in any version of Bash (from somewhere after 2.05b):

echo "${array[@]: -1:1}"

Larger negative offsets select farther from the end of the array. Note the space before the minus sign in the older form. It is required.

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