例子:
absolute="/foo/bar"
current="/foo/baz/foo"
# Magic
relative="../../bar"
我如何创造魔法(希望不是太复杂的代码…)?
例子:
absolute="/foo/bar"
current="/foo/baz/foo"
# Magic
relative="../../bar"
我如何创造魔法(希望不是太复杂的代码…)?
当前回答
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'","'$current'")')
其他回答
下面是一个shell脚本,它可以在不调用其他程序的情况下完成:
#! /bin/env bash
#bash script to find the relative path between two directories
mydir=${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
这个答案并没有解决问题的Bash部分,但是因为我试图使用这个问题中的答案在Emacs中实现这个功能,所以我就把它扔到那里。
Emacs实际上有一个开箱即用的函数:
ELISP> (file-relative-name "/a/b/c" "/a/b/c")
"."
ELISP> (file-relative-name "/a/b/c" "/a/b")
"c"
ELISP> (file-relative-name "/a/b/c" "/c/b")
"../../a/b/c"
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#./}
}
自2001年以来,它被内置到Perl中,因此它几乎可以在您能想象到的所有系统上工作,甚至VMS。
perl -le 'use File::Spec; print File::Spec->abs2rel(@ARGV)' FILE BASE
而且,解决方案很容易理解。
举个例子:
perl -le 'use File::Spec; print File::Spec->abs2rel(@ARGV)' $absolute $current
...会很好。
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
}