如果我在Bash中有一个这样的数组:

FOO=( a b c )

如何用逗号连接元素?例如,生成a b c。


当前回答

感谢@gniourf_gniourf对我迄今为止的最佳世界组合的详细评论。很抱歉发布的代码没有完全设计和测试。这是一个更好的尝试。

# join with separator
join_ws() { local d=$1 s=$2; shift 2 && printf %s "$s${@/#/$d}"; }

这种概念上的美是

(still) 100% pure bash ( thanks for explicitly pointing out that printf is a builtin as well. I wasn't aware about this before ... ) works with multi-character delimiters more compact and more complete and this time carefully thought over and long-term stress-tested with random substrings from shell scripts amongst others, covering use of shell special characters or control characters or no characters in both separator and / or parameters, and edge cases, and corner cases and other quibbles like no arguments at all. That doesn't guarantee there is no more bug, but it will be a little harder challenge to find one. BTW, even the currently top voted answers and related suffer from such things like that -e bug ...

附加的例子:

$ join_ws '' a b c
abc
$ join_ws ':' {1,7}{A..C}
1A:1B:1C:7A:7B:7C
$ join_ws -e -e
-e
$ join_ws $'\033[F' $'\n\n\n'  1.  2.  3.  $'\n\n\n\n'
3.
2.
1.
$ join_ws $ 
$

其他回答

也许,例如,

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

echo "$FOOJOIN"

通过重用@doesn't matters的解决方案,但通过避免${:1}的替换和中间变量的需要,使用了一个语句。

echo $(printf "%s," "${LIST[@]}" | cut -d "," -f 1-${#LIST[@]} )

printf有'格式字符串被重复使用,以满足参数。,这样字符串的连接就被记录下来了。然后诀窍是使用LIST长度来切割最后一个sperator,因为cut将只保留LIST的长度作为字段计数。

感谢@gniourf_gniourf对我迄今为止的最佳世界组合的详细评论。很抱歉发布的代码没有完全设计和测试。这是一个更好的尝试。

# join with separator
join_ws() { local d=$1 s=$2; shift 2 && printf %s "$s${@/#/$d}"; }

这种概念上的美是

(still) 100% pure bash ( thanks for explicitly pointing out that printf is a builtin as well. I wasn't aware about this before ... ) works with multi-character delimiters more compact and more complete and this time carefully thought over and long-term stress-tested with random substrings from shell scripts amongst others, covering use of shell special characters or control characters or no characters in both separator and / or parameters, and edge cases, and corner cases and other quibbles like no arguments at all. That doesn't guarantee there is no more bug, but it will be a little harder challenge to find one. BTW, even the currently top voted answers and related suffer from such things like that -e bug ...

附加的例子:

$ join_ws '' a b c
abc
$ join_ws ':' {1,7}{A..C}
1A:1B:1C:7A:7B:7C
$ join_ws -e -e
-e
$ join_ws $'\033[F' $'\n\n\n'  1.  2.  3.  $'\n\n\n\n'
3.
2.
1.
$ join_ws $ 
$

还有另一个解决方案:

#!/bin/bash
foo=('foo bar' 'foo baz' 'bar baz')
bar=$(printf ",%s" "${foo[@]}")
bar=${bar:1}

echo $bar

编辑:相同,但用于多字符可变长度分隔符:

#!/bin/bash
separator=")|(" # e.g. constructing regex, pray it does not contain %s
foo=('foo bar' 'foo baz' 'bar baz')
regex="$( printf "${separator}%s" "${foo[@]}" )"
regex="${regex:${#separator}}" # remove leading separator
echo "${regex}"
# Prints: foo bar)|(foo baz)|(bar baz

这与现有的解决方案并没有太大的不同,但它避免了使用单独的函数,不修改父shell中的IFS,并且都在一行中:

arr=(a b c)
printf '%s\n' "$(IFS=,; printf '%s' "${arr[*]}")"

导致

a,b,c

限制:分隔符不能超过一个字符。


可以化简为

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

在这一点上,它基本上与Pascal的答案相同,但使用printf而不是echo,并将结果打印到stdout,而不是将其赋值给变量。