ifs
IFS (Internal Field Separator) is a special environment variable that defines the delimiter used for word splitting in Unix shells.
TLDR
View the current IFS value
$ echo "$IFS"
Change the IFS value
$ IFS="[:]"
Reset IFS to default
$ IFS=$' \t\n'
Temporarily change the IFS value in a subshell
$ (IFS="[:]"; echo "[one:two:three]")