有点晚了，但你可以用这个:

#!/bin/bash
# isPicture.sh

FILE=$1
FNAME=$(basename "$FILE") # Filename, without directory
EXT="${FNAME##*.}" # Extension

FORMATS=(jpeg JPEG jpg JPG png PNG gif GIF svg SVG tiff TIFF)

NOEXT=( ${FORMATS[@]/$EXT} ) # Formats without the extension of the input file

# If it is a valid extension, then it should be removed from ${NOEXT},
#+making the lengths inequal.
if ! [ ${#NOEXT[@]} != ${#FORMATS[@]} ]; then
    echo "The extension '"$EXT"' is not a valid image extension."
    exit
fi

我的版本的正则表达式技术，已经建议:

values=(foo bar)
requestedValue=bar

requestedValue=${requestedValue##[[:space:]]}
requestedValue=${requestedValue%%[[:space:]]}
[[ "${values[@]/#/X-}" =~ "X-${requestedValue}" ]] || echo "Unsupported value"

What's happening here is that you're expanding the entire array of supported values into words and prepending a specific string, "X-" in this case, to each of them, and doing the same to the requested value. If this one is indeed contained in the array, then the resulting string will at most match one of the resulting tokens, or none at all in the contrary. In the latter case the || operator triggers and you know you're dealing with an unsupported value. Prior to all of that the requested value is stripped of all leading and trailing whitespace through standard shell string manipulation.

我相信它是干净而优雅的，尽管如果支持的值数组特别大，我不太确定它的性能如何。

考虑到:

array=("something to search for" "a string" "test2000")
elem="a string"

然后简单检查一下:

if c=$'\x1E' && p="${c}${elem} ${c}" && [[ ! "${array[@]/#/${c}} ${c}" =~ $p ]]; then
  echo "$elem exists in array"
fi

在哪里

c is element separator
p is regex pattern

(单独分配p，而不是直接在[[]]中使用表达式的原因是为了保持bash 4的兼容性)

这是一个小小的贡献:

array=(word "two words" words)  
search_string="two"  
match=$(echo "${array[@]:0}" | grep -o $search_string)  
[[ ! -z $match ]] && echo "found !"  

注意:这种方法不区分大小写“两个单词”，但在问题中不需要这样做。

The answer with most votes is very concise and clean, but it can have false positives when a space is part of one of the array elements. This can be overcome when changing IFS and using "${array[*]}" instead of "${array[@]}". The method is identical, but it looks less clean. By using "${array[*]}", we print all elements of $array, separated by the first character in IFS. So by choosing a correct IFS, you can overcome this particular issue. In this particular case, we decide to set IFS to an uncommon character $'\001' which stands for Start of Heading (SOH)

$ array=("foo bar" "baz" "qux")
$ IFS=$'\001'
$ [[ "$IFS${array[*]}$IFS" =~ "${IFS}foo${IFS}" ]] && echo yes || echo no
no
$ [[ "$IFS${array[*]}$IFS" =~ "${IFS}foo bar${IFS}" ]] && echo yes || echo no
yes
$ unset IFS

这解决了大多数假阳性问题，但需要一个好的IFS选择。

注意:如果之前设置了IFS，最好保存并重新设置，而不是使用未设置的IFS

相关:

访问bash命令行参数$@ vs $*

一行的解决方案

printf '%s\0' "${myarray[@]}" | grep -F -x -z -- 'myvalue'

解释

printf语句打印数组中的每个元素，以空字符分隔。

grep语句使用以下标志来匹配一个包含myvalue字符串的项(不多不少):

-z/——null-data -行以0字节而不是换行符结束。 -f /——fixed-strings -将pattern解释为固定字符串，而不是正则表达式。 -x/——line-regexp -只选择与整行完全匹配的匹配项。 ——-标记命令行选项的结束，使Grep处理“myvalue”作为一个非选项参数，即使它以破折号开始

为什么我们使用空字节\0而不是换行符\n?数组的元素实际上可能包含换行符。(如果您知道它没有，请随意删除-z grep选项，并将%s\n替换为您的第一个printf参数。)

使用

把这个放进一个if…然后声明:

if printf '%s\0' "${myarray[@]}" | grep -Fxqz -- 'myvalue'; then
    # ...
fi

我在grep表达式中添加了-q标志，这样它就不会打印匹配项;它只会将匹配的存在视为“真”。

更新:感谢presto8指出——line-regexp标志。谢谢Tino，你指出了数组项中可以存在换行符的情况。