Bash：为什么printf不尊重换行符？

Question

Why does this bash script (at bottom) not output the newline? The result is:

filesonetwothree

instead of

files
one
two
three

Here's the script:

files=()
files+="one"
files+="two"
files+="three"

printf "\nfiles"
for file in "${files[@]}"
do
    printf "$file\n"
done

NOTE: This is on a Mac running macOS Sierra

Answer 1

The following will make your issue very clear:

files=()
files+="one"
files+="two"
files+="three"
declare -p files

...emits as output:

declare -a files='([0]="onetwothree")'

...so, you were appending to the first element of the array , not adding new elements to the array's end.

---

To correctly append to an array, use the following instead:

files=()
files+=("one")
files+=("two")
files+=("three")
declare -p files

...which emits:

declare -a files='([0]="one" [1]="two" [2]="three")'

---

In either case, to print your array one-line-to-an-element, use a format string with a newline, and pass your array elements as subsequent arguments:

printf '%s\n' "${files[@]}"