arrays - 从 ksh 数组中删除特定值

Question

我有一个在 ksh 中使用的自定义 .profile，下面是我创建的一个函数，用于从名称过于复杂或过长的目录中来回跳转。

如您所见，路径名存储在数组 (BOOKMARKS[]) 中，以跟踪它们并在以后引用它们。我希望能够使用 case 语句(或必要时使用 OPTARG)从数组中删除某些值，以便我只需键入 bmk -d # 即可删除关联索引处的路径。

我摆弄了array +A和-A，但它最终搞砸了我的数组(注释掉的代码中剩下的内容可能不太漂亮......我没有'不校对它)。

关于如何创建该功能有什么建议/提示吗？谢谢!

# To bookmark the current directory you are in for easy navigation back and forth from multiple non-aliased directories
# Use like 'bmk' (sets the current directory to a bookmark number) to go back to this directory, i.e. type 'bmk 3' (for the 3rd)
# To find out what directories are linked to which numbers, type 'bmk -l' (lowercase L)
# For every new directory bookmarked, the number will increase so the first time you run 'bmk' it will be 1 then 2,3,4...etc. for every consecutive run therea
fter
# TODO: finish -d (delete bookmark entry) function
make_bookmark()
{
        if [[ $# -eq 0 ]]; then
                BOOKMARKS[${COUNTER}]=${PWD}
                (( COUNTER=COUNTER+1 ))
        else
                case $1 in
                        -l)     NUM_OF_ELEMENTS=${#BOOKMARKS[*]}

                                while [[ ${COUNTER} -lt ${NUM_OF_ELEMENTS} ]]
                                do
                                        (( ACTUAL_NUM=i+1 ))
                                        echo ${ACTUAL_NUM}":"${BOOKMARKS[${i}]}
                                        (( COUNTER=COUNTER+1 ))
                                done
                                break ;;


                       #-d)    ACTUAL_NUM=$2
                                #(( REMOVE=${ACTUAL_NUM}-1 ))
                                #echo "Removing path ${BOOKMARKS[${REMOVE}]} from 'bmk'..."
                                #NUM_OF_ELEMENTS=${#BOOKMARKS[*]}

                                #while [[ ${NUM_OF_ELEMENTS} -gt 0 ]]
                                #do
                                        #if [[ ${NUM_OF_ELEMENTS} -ne ${ACTUAL_NUM} ]]; then
                                        #       TEMP_ARR=$(echo "${BOOKMARKS[*]}")
                                        #       (( NUM_OF_ELEMENTS=${NUM_OF_ELEMENTS}-1 ))
                                        #fi
                                        #echo $TEMP_ARR
                                #done
                                #break
                                #for VALUE in ${TEMP_ARR}
                                #do
                                #       set +A BOOKMARK ${TEMP_ARR}
                                #done
                                #echo ${BOOKMARK[*]}

                                #break ;;

                        *)      (( INDEX=$1-1 ))
                                cd ${BOOKMARKS[${INDEX}]}
                                break ;;
                esac
        fi
}

Answer 1

Korn shell(以及 Bash 和其他)中的数组是稀疏的，因此如果您使用 unset 删除数组的成员，您将无法将数组的大小用作最后一个成员的索引和其他限制。

这里有一些有用的片段(第二个 for 循环是您可以立即使用的):

array=(1 2 3)
unset array[2]
echo ${array[2]}          # null
indices=(${!array[@]})    # create an array of the indices of "array"
size=${#indices[@]}       # the size of "array" is the number of indices into it
size=${#array[@]}         # same
echo ${array[@]: -1}      # you can use slices to get array elements, -1 is the last one, etc.
for element in ${array[@]}; do    # iterate over the array without an index

for index in ${indices[@]}        # iterate over the array WITH an index
do
    echo "Index: ${index}, Element: ${array[index]}"
done

for index in ${!array[@]}         # iterate over the array WITH an index, directly

最后一个可以消除对计数器的需要。

这里有一些更方便的技巧:

array+=("new element")    # append a new element without referring to an index
((counter++))             # shorter than ((counter=counter+1)) or ((counter+=1))
if [[ $var == 3 ]]        # you can use the more "natural" comparison operators inside double square brackets
while [[ $var < 11 ]]     # another example
echo ${array[${index}-1]  # math inside an array subscript

这一切都假设 ksh93，有些功能在早期版本中可能无法工作。