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。

这是我的版本。这是基于@Offirmo的回答。我使它与dash兼容，并修复了以下测试用例失败:

sh - compute-relative。“a / b / c - de - f / g " / a / b / c / def / g /" --> "../.. f - g - "

Now:

CT_FindRelativePath”a / b / c - de - f / g " / a / b / c / def / g /" --> "../../../ def - g”

查看代码:

# both $1 and $2 are absolute paths beginning with /
# returns relative path to $2/$target from $1/$source
CT_FindRelativePath()
{
    local insource=$1
    local intarget=$2

    # Ensure both source and target end with /
    # This simplifies the inner loop.
    #echo "insource : \"$insource\""
    #echo "intarget : \"$intarget\""
    case "$insource" in
        */) ;;
        *) source="$insource"/ ;;
    esac

    case "$intarget" in
        */) ;;
        *) target="$intarget"/ ;;
    esac

    #echo "source : \"$source\""
    #echo "target : \"$target\""

    local common_part=$source # for now

    local result=""

    #echo "common_part is now : \"$common_part\""
    #echo "result is now      : \"$result\""
    #echo "target#common_part : \"${target#$common_part}\""
    while [ "${target#$common_part}" = "${target}" -a "${common_part}" != "//" ]; 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
        if [ -z "${result}" ]; then
            result="../"
        else
            result="../$result"
        fi
        #echo "(w) common_part is now : \"$common_part\""
        #echo "(w) result is now      : \"$result\""
        #echo "(w) target#common_part : \"${target#$common_part}\""
    done

    #echo "(f) common_part is     : \"$common_part\""

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

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

    if [ -n "${result}" -a -n "${forward_part}" ]; then
        #echo "(simple concat)"
        result="$result$forward_part"
    elif [ -n "${forward_part}" ]; then
        result="$forward_part"
    fi
    #echo "result = \"$result\""

    # if a / was added to target and result ends in / then remove it now.
    if [ "$intarget" != "$target" ]; then
        case "$result" in
            */) result=$(echo "$result" | awk '{ string=substr($0, 1, length($0)-1); print string; }' ) ;;
        esac
    fi

    echo $result

    return 0
}

$ python -c "import os.path; print os.path.relpath('/foo/bar', '/foo/baz/foo')"

给:

../../bar

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#./}
}

我将只使用Perl来完成这个不那么简单的任务:

absolute="/foo/bar"
current="/foo/baz/foo"

# Perl is magic
relative=$(perl -MFile::Spec -e 'print File::Spec->abs2rel("'$absolute'","'$current'")')

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