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。
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
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 "${regex}"
# Prints: foo bar)|(foo baz)|(bar baz
其他回答
Printf解决方案,接受任何长度的分隔符(基于@doesn't matters answer)
#/!bin/bash
foo=('foo bar' 'foo baz' 'bar baz')
sep=',' # can be of any length
bar=$(printf "${sep}%s" "${foo[@]}")
bar=${bar:${#sep}}
echo $bar
现在我用的是:
TO_IGNORE=(
E201 # Whitespace after '('
E301 # Expected N blank lines, found M
E303 # Too many blank lines (pep8 gets confused by comments)
)
ARGS="--ignore `echo ${TO_IGNORE[@]} | tr ' ' ','`"
这是可行的,但是(在一般情况下)如果数组元素中有空格,将会严重破坏。
(对于那些感兴趣的人,这是一个围绕pep8.py的包装器脚本)
我将数组作为字符串回显,然后将空格转换为换行,然后使用粘贴将所有内容连接到一行,如下所示:
tr " " "\n" <<< "$FOO" |粘贴-sd, -
结果:
a, b, c
对我来说,这似乎是最快最干净的!
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。
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 $
$