如何排序在BASH数组 [英] How to sort an array in BASH

问题描述

我在Bash的数组，例如：

I have an array in Bash, for example:

array=(a c b f 3 5)

我要排序的数组。不只是显示在排序方式的内容，但要获得与排序元素的数组。新的排序数组可以是一个完全新的或旧的。

I need to sort the array. Not just displaying the content in a sorted way, but to get a new array with the sorted elements. The new sorted array can be a completely new one or the old one.

推荐答案

下面是一个纯粹的Bash快速排序实现：

Here's a pure Bash quicksort implementation:

#!/bin/bash

# quicksorts positional arguments
# return is in array qsort_ret
qsort() {
   local pivot i smaller=() larger=()
   qsort_ret=()
   (($#==0)) && return 0
   pivot=$1
   shift
   for i; do
      if [[ $i < $pivot ]]; then
         smaller+=( "$i" )
      else
         larger+=( "$i" )
      fi
   done
   qsort "${smaller[@]}"
   smaller=( "${qsort_ret[@]}" )
   qsort "${larger[@]}"
   larger=( "${qsort_ret[@]}" )
   qsort_ret=( "${smaller[@]}" "$pivot" "${larger[@]}" )
}

使用的，如，

$ array=(a c b f 3 5)
$ qsort "${array[@]}"
$ declare -p qsort_ret
declare -a qsort_ret='([0]="3" [1]="5" [2]="a" [3]="b" [4]="c" [5]="f")'

这实现递归......所以这里是一个反复的快速排序：

This implementation is recursive… so here's an iterative quicksort:

#!/bin/bash

# quicksorts positional arguments
# return is in array qsort_ret
# Note: iterative, NOT recursive! :)
qsort() {
   (($#==0)) && return 0
   local stack=( 0 $(($#-1)) ) beg end i pivot smaller larger
   qsort_ret=("$@")
   while ((${#stack[@]})); do
      beg=${stack[0]}
      end=${stack[1]}
      stack=( "${stack[@]:2}" )
      smaller=() larger=()
      pivot=${qsort_ret[beg]}
      for ((i=beg+1;i<=end;++i)); do
         if [[ "${qsort_ret[i]}" < "$pivot" ]]; then
            smaller+=( "${qsort_ret[i]}" )
         else
            larger+=( "${qsort_ret[i]}" )
         fi
      done
      qsort_ret=( "${qsort_ret[@]:0:beg}" "${smaller[@]}" "$pivot" "${larger[@]}" "${qsort_ret[@]:end+1}" )
      if ((${#smaller[@]}>=2)); then stack+=( "$beg" "$((beg+${#smaller[@]}-1))" ); fi
      if ((${#larger[@]}>=2)); then stack+=( "$((end-${#larger[@]}+1))" "$end" ); fi
   done
}

在这两种情况下，你可以改变你使用的顺序：我用字符串比较，但可以使用算术比较，比较WRT文件修改时间等只是用适当的测试;你甚至可以使它更通用的，有它使用的是测试功能的使用，例如第一个参数，

In both cases, you can change the order you use: I used string comparisons, but you can use arithmetic comparisons, compare wrt file modification time, etc. just use the appropriate test; you can even make it more generic and have it use a first argument that is the test function use, e.g.,

#!/bin/bash

# quicksorts positional arguments
# return is in array qsort_ret
# Note: iterative, NOT recursive! :)
# First argument is a function name that takes two arguments and compares them
qsort() {
   (($#<=1)) && return 0
   local compare_fun=$1
   shift
   local stack=( 0 $(($#-1)) ) beg end i pivot smaller larger
   qsort_ret=("$@")
   while ((${#stack[@]})); do
      beg=${stack[0]}
      end=${stack[1]}
      stack=( "${stack[@]:2}" )
      smaller=() larger=()
      pivot=${qsort_ret[beg]}
      for ((i=beg+1;i<=end;++i)); do
         if "$compare_fun" "${qsort_ret[i]}" "$pivot"; then
            smaller+=( "${qsort_ret[i]}" )
         else
            larger+=( "${qsort_ret[i]}" )
         fi
      done
      qsort_ret=( "${qsort_ret[@]:0:beg}" "${smaller[@]}" "$pivot" "${larger[@]}" "${qsort_ret[@]:end+1}" )
      if ((${#smaller[@]}>=2)); then stack+=( "$beg" "$((beg+${#smaller[@]}-1))" ); fi
      if ((${#larger[@]}>=2)); then stack+=( "$((end-${#larger[@]}+1))" "$end" ); fi
   done
}

然后你就可以有这样的比较函数：

Then you can have this comparison function:

compare_mtime() { [[ $1 -nt $2 ]]; }

和使用：

$ qsort compare_mtime *
$ declare -p qsort_ret

有被修改的时间（最新的在前）排列当前文件夹中的文件

to have the files in current folder sorted by modification time (newest first).

请注意。这些功能都是纯击！没有外部公用事业和无子shell！他们是安全的WRT如果您有任何有趣的符号（空格，换行字符，字符水珠，等等）。

NOTE. These functions are pure Bash! no external utilities, and no subshells! they are safe wrt any funny symbols you may have (spaces, newline characters, glob characters, etc.).

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