在Bash中,测试数组是否包含某个值的最简单方法是什么?
当前回答
@ghostdog74关于使用大小写逻辑检查数组包含特定值的回答的一个小补充:
myarray=(one two three)
word=two
case "${myarray[@]}" in ("$word "*|*" $word "*|*" $word") echo "found" ;; esac
或者打开extglob选项,你可以这样做:
myarray=(one two three)
word=two
shopt -s extglob
case "${myarray[@]}" in ?(*" ")"$word"?(" "*)) echo "found" ;; esac
我们也可以用if语句:
myarray=(one two three)
word=two
if [[ $(printf "_[%s]_" "${myarray[@]}") =~ .*_\[$word\]_.* ]]; then echo "found"; fi
其他回答
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
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 $*
for i in "${array[@]}"
do
if [ "$i" -eq "$yourValue" ] ; then
echo "Found"
fi
done
字符串:
for i in "${array[@]}"
do
if [ "$i" == "$yourValue" ] ; then
echo "Found"
fi
done
这是一个小小的贡献:
array=(word "two words" words)
search_string="two"
match=$(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。
我通常编写这类实用程序来操作变量的名称,而不是变量的值,这主要是因为bash不能通过引用传递变量。
下面是一个使用数组名称的版本:
function array_contains # array value
{
[[ -n "$1" && -n "$2" ]] || {
echo "usage: array_contains <array> <value>"
echo "Returns 0 if array contains value, 1 otherwise"
return 2
}
eval 'local values=("${'$1'[@]}")'
local element
for element in "${values[@]}"; do
[[ "$element" == "$2" ]] && return 0
done
return 1
}
这样,问题示例就变成:
array_contains A "one" && echo "contains one"
etc.