Splitting input into an array

readarray

readarray makes it really easy to split input into an array based on new lines. Say we have this file as input:

123
456
789

Then we can split like so:

readarray -t name_for_array < ./input.text

# Print all elements
echo "${name_for_array[@]}"

# Print element by index

echo "${name_for_array[1]}"
456

If we want to read a string directly:

readarray -t new_name_for_array <<< "here
is
some
text"

echo "${new_name_for_array[1]}"
is

The -t flag removes the trailing newline

See more: https://linuxhint.com/split-string-array-bash/

read

For delimiters other than a space we have to use read, combined with IFS the Internal Field Separator.

For example, to split by comma:

# comma-input.txt
something,something else,something more

IFS=',' read -a arr < ./comma_inputs.txt

We use the -a flag to signal that we want each item read returned as an element in an array

mapfile

We can use mapfile to read the lines of a input file in set segments.

For the following file:

line one
line two
line three
line four

We could generate the following output:

-----SNIP-----
line one
line two
-----SNIP-----
line three
line four

With:

while mapfile -t -n 2 ary && ((${#ary[@]})); do
  printf '%s\n' "${ary[@]}"
  printf -- '--- SNIP ---\n'
 done < $testInput

So, while there are input lines, map each line into an array and return it in groups of 2.

1.5 KiB Raw Blame History

Splitting input into an array

readarray

read

mapfile

1.5 KiB

Raw Blame History