How to persist variables in a loop from a find command?

The usual way is to use a pipe:

find . -name '*.jpg' | while read f do;
    some_command "$f"
done

There are two problems here. First, this won’t work if paths have spaces or other blank characters in them. Second, bash actually forks a sub-process when using the pipe, so everything that is done within the “while” loop is executed in a sub-process. If variables are set in this loop, they won’t be available outside the loop.

Here is a better way:

a=
i=0
while IFS= read -r -d $'\0' f; do
    a[i++]="$f"
done < <(find . -name '*.jpg' -print0)

The -print0 option for find will separate entries using the null character instead of the newline character, thus allowing spaces and other blanks in path names. Using redirection in the example above runs find in a subshell, rather than the loop itself, thus preserving variables after the loop.