Read file content into an array

Question

I need to read the lines of a text file into an array in Bash. The simple approach

arr=( $(cat myfile.txt) )

does not work for me, because the lines may contain whitespace, so an input like this

foo bar
baz

would result in an array

[ "foo", "bar", "baz" ]

instead of the desired

[ "foo bar", "baz" ]

I can get the desired result by using a loop like this:

declare -a arr=()
while read -r line; do
  arr+=( "$line" )
done < myfile.txt

but that seems a bit overkill.

Comments

Are you asking yourself questions?

– anonymous 2020-08-31 ✍

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I'm generating content by answering questions to problems I've encountered to get this thing off the ground, and maybe attract some users.

– Ansgar Wiechers 2020-08-31 ✍

Answer 1

Since version 4 Bash has a builtin command mapfile (which also has a synonym readarray) that does what you're asking:

mapfile -t arr < myfile.txt
readarray -t arr < myfile.txt

The option -t is to strip trailing newlines from the input.

mapfile and readarray do the same thing, but personally I'd probably prefer the latter since it's clearer what the command does when you read the script.