下面是一个100%纯Bash函数，它可以完成这项工作:

join() {
    # $1 is return variable name
    # $2 is sep
    # $3... are the elements to join
    local retname=$1 sep=$2 ret=$3
    shift 3 || shift $(($#))
    printf -v "$retname" "%s" "$ret${@/#/$sep}"
}

看:

$ a=( one two "three three" four five )
$ join joineda " and " "${a[@]}"
$ echo "$joineda"
one and two and three three and four and five
$ join joinedb randomsep "only one element"
$ echo "$joinedb"
only one element
$ join joinedc randomsep
$ echo "$joinedc"

$ a=( $' stuff with\nnewlines\n' $'and trailing newlines\n\n' )
$ join joineda $'a sep with\nnewlines\n' "${a[@]}"
$ echo "$joineda"
 stuff with
newlines
a sep with
newlines
and trailing newlines


$

这甚至保留了末尾的换行符，并且不需要一个子shell来获得函数的结果。如果你不喜欢printf -v(为什么你不喜欢它?)并传递一个变量名，你当然可以为返回的字符串使用一个全局变量:

join() {
    # $1 is sep
    # $2... are the elements to join
    # return is in global variable join_ret
    local sep=$1 IFS=
    join_ret=$2
    shift 2 || shift $(($#))
    join_ret+="${*/#/$sep}"
}

这个特别适用于busybox的sh和$@:

$ FOO=(a b c)
$ printf '%s\n' "${FOO[@]}" | paste -sd,
a,b,c

Or:

join_by() {
    local d=$1
    shift
    printf '%s\n' "$@" | paste -sd "$d"
}
join_by , "${FOO[@]}"  # a,b,c

我的尝试。

$ array=(one two "three four" five)
$ echo "${array[0]}$(printf " SEP %s" "${array[@]:1}")"
one SEP two SEP three four SEP five

s=$(IFS=, eval 'echo "${FOO[*]}"')

我相信这是最短的解决方案，正如Benamin W.已经提到的:

(IFS=,; printf %s "${a[*]}")

想要添加，如果你使用zsh，你可以删除子shell:

IFS=, printf %s "${a[*]}"

测试:

a=(1 'a b' 3)
IFS=, printf %s "${a[*]}"
1,a b,3

也许,例如,

SAVE_IFS="$IFS"
IFS=","
FOOJOIN="${FOO[*]}"
IFS="$SAVE_IFS"

echo "$FOOJOIN"