这是对@pini目前评分最高的解决方案(遗憾的是，它只处理少数情况)的更正，全功能改进

提醒:'-z'测试如果字符串是零长度(=空)，'-n'测试如果字符串不是空。

# both $1 and $2 are absolute paths beginning with /
# returns relative path to $2/$target from $1/$source
source=$1
target=$2

common_part=$source # for now
result="" # for now

while [[ "${target#$common_part}" == "${target}" ]]; do
    # no match, means that candidate common part is not correct
    # go up one level (reduce common part)
    common_part="$(dirname $common_part)"
    # and record that we went back, with correct / handling
    if [[ -z $result ]]; then
        result=".."
    else
        result="../$result"
    fi
done

if [[ $common_part == "/" ]]; then
    # special case for root (no common path)
    result="$result/"
fi

# since we now have identified the common part,
# compute the non-common part
forward_part="${target#$common_part}"

# and now stick all parts together
if [[ -n $result ]] && [[ -n $forward_part ]]; then
    result="$result$forward_part"
elif [[ -n $forward_part ]]; then
    # extra slash removal
    result="${forward_part:1}"
fi

echo $result

测试用例:

compute_relative.sh "/A/B/C" "/A"           -->  "../.."
compute_relative.sh "/A/B/C" "/A/B"         -->  ".."
compute_relative.sh "/A/B/C" "/A/B/C"       -->  ""
compute_relative.sh "/A/B/C" "/A/B/C/D"     -->  "D"
compute_relative.sh "/A/B/C" "/A/B/C/D/E"   -->  "D/E"
compute_relative.sh "/A/B/C" "/A/B/D"       -->  "../D"
compute_relative.sh "/A/B/C" "/A/B/D/E"     -->  "../D/E"
compute_relative.sh "/A/B/C" "/A/D"         -->  "../../D"
compute_relative.sh "/A/B/C" "/A/D/E"       -->  "../../D/E"
compute_relative.sh "/A/B/C" "/D/E/F"       -->  "../../../D/E/F"

kasku和Pini的答案略有改进，空格更好，允许传递相对路径:

#!/bin/bash
# both $1 and $2 are paths
# returns $2 relative to $1
absolute=`readlink -f "$2"`
current=`readlink -f "$1"`
# Perl is magic
# Quoting horror.... spaces cause problems, that's why we need the extra " in here:
relative=$(perl -MFile::Spec -e "print File::Spec->abs2rel(q($absolute),q($current))")

echo $relative

假设您已经安装了:bash、pwd、dirname、echo;relpath是

#!/bin/bash
s=$(cd ${1%%/};pwd); d=$(cd $2;pwd); b=; while [ "${d#$s/}" == "${d}" ]
do s=$(dirname $s);b="../${b}"; done; echo ${b}${d#$s/}

我从pini和其他一些想法中得到了答案

注意:这要求两个路径都是现有文件夹。文件将无法工作。

我把你的问题作为一个挑战，用“可移植的”shell代码来编写它，即。

考虑到POSIX外壳 没有数组之类的bashisms 避免像打瘟疫一样打外部电话。脚本中没有一个分叉!这使得它非常快，特别是在有显著分叉开销的系统上，比如cygwin。 必须处理路径名中的glob字符(*，?，[，])

它运行在任何POSIX兼容shell (zsh, bash, ksh, ash, busybox，…)上。它甚至包含一个测试套件来验证其操作。路径名的规范化留作练习。: -)

#!/bin/sh

# Find common parent directory path for a pair of paths.
# Call with two pathnames as args, e.g.
# commondirpart foo/bar foo/baz/bat -> result="foo/"
# The result is either empty or ends with "/".
commondirpart () {
   result=""
   while test ${#1} -gt 0 -a ${#2} -gt 0; do
      if test "${1%${1#?}}" != "${2%${2#?}}"; then   # First characters the same?
         break                                       # No, we're done comparing.
      fi
      result="$result${1%${1#?}}"                    # Yes, append to result.
      set -- "${1#?}" "${2#?}"                       # Chop first char off both strings.
   done
   case "$result" in
   (""|*/) ;;
   (*)     result="${result%/*}/";;
   esac
}

# Turn foo/bar/baz into ../../..
#
dir2dotdot () {
   OLDIFS="$IFS" IFS="/" result=""
   for dir in $1; do
      result="$result../"
   done
   result="${result%/}"
   IFS="$OLDIFS"
}

# Call with FROM TO args.
relativepath () {
   case "$1" in
   (*//*|*/./*|*/../*|*?/|*/.|*/..)
      printf '%s\n' "'$1' not canonical"; exit 1;;
   (/*)
      from="${1#?}";;
   (*)
      printf '%s\n' "'$1' not absolute"; exit 1;;
   esac
   case "$2" in
   (*//*|*/./*|*/../*|*?/|*/.|*/..)
      printf '%s\n' "'$2' not canonical"; exit 1;;
   (/*)
      to="${2#?}";;
   (*)
      printf '%s\n' "'$2' not absolute"; exit 1;;
   esac

   case "$to" in
   ("$from")   # Identical directories.
      result=".";;
   ("$from"/*) # From /x to /x/foo/bar -> foo/bar
      result="${to##$from/}";;
   ("")        # From /foo/bar to / -> ../..
      dir2dotdot "$from";;
   (*)
      case "$from" in
      ("$to"/*)       # From /x/foo/bar to /x -> ../..
         dir2dotdot "${from##$to/}";;
      (*)             # Everything else.
         commondirpart "$from" "$to"
         common="$result"
         dir2dotdot "${from#$common}"
         result="$result/${to#$common}"
      esac
      ;;
   esac
}

set -f # noglob

set -x
cat <<EOF |
/ / .
/- /- .
/? /? .
/?? /?? .
/??? /??? .
/?* /?* .
/* /* .
/* /** ../**
/* /*** ../***
/*.* /*.** ../*.**
/*.??? /*.?? ../*.??
/[] /[] .
/[a-z]* /[0-9]* ../[0-9]*
/foo /foo .
/foo / ..
/foo/bar / ../..
/foo/bar /foo ..
/foo/bar /foo/baz ../baz
/foo/bar /bar/foo  ../../bar/foo
/foo/bar/baz /gnarf/blurfl/blubb ../../../gnarf/blurfl/blubb
/foo/bar/baz /gnarf ../../../gnarf
/foo/bar/baz /foo/baz ../../baz
/foo. /bar. ../bar.
EOF
while read FROM TO VIA; do
   relativepath "$FROM" "$TO"
   printf '%s\n' "FROM: $FROM" "TO:   $TO" "VIA:  $result"
   if test "$result" != "$VIA"; then
      printf '%s\n' "OOOPS! Expected '$VIA' but got '$result'"
   fi
done

# vi: set tabstop=3 shiftwidth=3 expandtab fileformat=unix :

下面是一个shell脚本，它可以在不调用其他程序的情况下完成:

#! /bin/env bash 

#bash script to find the relative path between two directories

mydir=${0%/}
mydir=${0%/*}
creadlink="$mydir/creadlink"

shopt -s extglob

relpath_ () {
        path1=$("$creadlink" "$1")
        path2=$("$creadlink" "$2")
        orig1=$path1
        path1=${path1%/}/
        path2=${path2%/}/

        while :; do
                if test ! "$path1"; then
                        break
                fi
                part1=${path2#$path1}
                if test "${part1#/}" = "$part1"; then
                        path1=${path1%/*}
                        continue
                fi
                if test "${path2#$path1}" = "$path2"; then
                        path1=${path1%/*}
                        continue
                fi
                break
        done
        part1=$path1
        path1=${orig1#$part1}
        depth=${path1//+([^\/])/..}
        path1=${path2#$path1}
        path1=${depth}${path2#$part1}
        path1=${path1##+(\/)}
        path1=${path1%/}
        if test ! "$path1"; then
                path1=.
        fi
        printf "$path1"

}

relpath_test () {
        res=$(relpath_ /path1/to/dir1 /path1/to/dir2 )
        expected='../dir2'
        test_results "$res" "$expected"

        res=$(relpath_ / /path1/to/dir2 )
        expected='path1/to/dir2'
        test_results "$res" "$expected"

        res=$(relpath_ /path1/to/dir2 / )
        expected='../../..'
        test_results "$res" "$expected"

        res=$(relpath_ / / )
        expected='.'
        test_results "$res" "$expected"

        res=$(relpath_ /path/to/dir2/dir3 /path/to/dir1/dir4/dir4a )
        expected='../../dir1/dir4/dir4a'
        test_results "$res" "$expected"

        res=$(relpath_ /path/to/dir1/dir4/dir4a /path/to/dir2/dir3 )
        expected='../../../dir2/dir3'
        test_results "$res" "$expected"

        #res=$(relpath_ . /path/to/dir2/dir3 )
        #expected='../../../dir2/dir3'
        #test_results "$res" "$expected"
}

test_results () {
        if test ! "$1" = "$2"; then
                printf 'failed!\nresult:\nX%sX\nexpected:\nX%sX\n\n' "$@"
        fi
}

#relpath_test

来源:http://www.ynform.org/w/Pub/Relpath

我使用的macOS默认情况下没有realpath命令，所以我做了一个纯bash函数来计算它。

#!/bin/bash

##
# print a relative path from "source folder" to "target file"
#
# params:
#  $1 - target file, can be a relative path or an absolute path.
#  $2 - source folder, can be a relative path or an absolute path.
#
# test:
#  $ mkdir -p ~/A/B/C/D; touch ~/A/B/C/D/testfile.txt; touch ~/A/B/testfile.txt
#
#  $ getRelativePath ~/A/B/C/D/testfile.txt  ~/A/B
#  $ C/D/testfile.txt
#  
#  $ getRelativePath ~/A/B/testfile.txt  ~/A/B/C
#  $ ../testfile.txt
#
#  $ getRelativePath ~/A/B/testfile.txt  /
#  $ home/bunnier/A/B/testfile.txt 
#
function getRelativePath(){
    local targetFilename=$(basename $1)
    local targetFolder=$(cd $(dirname $1);pwd) # absolute target folder path
    local currentFolder=$(cd $2;pwd) # absulute source folder
    local result=.

    while [ "$currentFolder" != "$targetFolder" ];do
      if [[ "$targetFolder" =~ "$currentFolder"* ]];then
          pointSegment=${targetFolder#$currentFolder}
          result=$result/${pointSegment#/}
          break
      fi  
      result="$result"/..
      currentFolder=$(dirname $currentFolder)
    done

    result=$result/$targetFilename
    echo ${result#./}
}