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
test.sh:
#!/bin/bash
cd /home/ubuntu
touch blah
TEST=/home/ubuntu/.//blah
echo TEST=$TEST
TMP=$(readlink -e "$TEST")
echo TMP=$TMP
REL=${TMP#$(pwd)/}
echo REL=$REL
测试:
$ ./test.sh
TEST=/home/ubuntu/.//blah
TMP=/home/ubuntu/blah
REL=blah
其他回答
#!/bin/sh
# Return relative path from canonical absolute dir path $1 to canonical
# absolute dir path $2 ($1 and/or $2 may end with one or no "/").
# Does only need POSIX shell builtins (no external command)
relPath () {
local common path up
common=${1%/} path=${2%/}/
while test "${path#"$common"/}" = "$path"; do
common=${common%/*} up=../$up
done
path=$up${path#"$common"/}; path=${path%/}; printf %s "${path:-.}"
}
# Return relative path from dir $1 to dir $2 (Does not impose any
# restrictions on $1 and $2 but requires GNU Core Utility "readlink"
# HINT: busybox's "readlink" does not support option '-m', only '-f'
# which requires that all but the last path component must exist)
relpath () { relPath "$(readlink -m "$1")" "$(readlink -m "$2")"; }
上面的shell脚本是受pini的启发(谢谢!)它会触发一个错误 在Stack Overflow的语法高亮显示模块中(至少在我的预览中是这样) 帧)。因此，如果高亮显示不正确，请忽略。
一些注意事项:
Removed errors and improved code without significantly increasing code length and complexity Put functionality into functions for easiness of use Kept functions POSIX compatible so that they (should) work with all POSIX shells (tested with dash, bash, and zsh in Ubuntu Linux 12.04) Used local variables only to avoid clobbering global variables and polluting the global name space Both directory paths DO NOT need to exist (requirement for my application) Pathnames may contain spaces, special characters, control characters, backslashes, tabs, ', ", ?, *, [, ], etc. Core function "relPath" uses POSIX shell builtins only but requires canonical absolute directory paths as parameters Extended function "relpath" can handle arbitrary directory paths (also relative, non-canonical) but requires external GNU core utility "readlink" Avoided builtin "echo" and used builtin "printf" instead for two reasons: Due to conflicting historical implementations of builtin "echo" it behaves differently in different shells -> POSIX recommends that printf is preferred over echo. Builtin "echo" of some POSIX shells will interpret some backslash sequences and thus corrupt pathnames containing such sequences To avoid unnecessary conversions, pathnames are used as they are returned and expected by shell and OS utilities (e.g. cd, ln, ls, find, mkdir; unlike python's "os.path.relpath" which will interpret some backslash sequences) Except for the mentioned backslash sequences the last line of function "relPath" outputs pathnames compatible to python: path=$up${path#"$common"/}; path=${path%/}; printf %s "${path:-.}" Last line can be replaced (and simplified) by line printf %s "$up${path#"$common"/}" I prefer the latter because Filenames can be directly appended to dir paths obtained by relPath, e.g.: ln -s "$(relpath "<fromDir>" "<toDir>")<file>" "<fromDir>" Symbolic links in the same dir created with this method do not have the ugly "./" prepended to the filename. If you find an error please contact linuxball (at) gmail.com and I'll try to fix it. Added regression test suite (also POSIX shell compatible)
回归测试的代码清单(只需将其附加到shell脚本):
############################################################################
# If called with 2 arguments assume they are dir paths and print rel. path #
############################################################################
test "$#" = 2 && {
printf '%s\n' "Rel. path from '$1' to '$2' is '$(relpath "$1" "$2")'."
exit 0
}
#######################################################
# If NOT called with 2 arguments run regression tests #
#######################################################
format="\t%-19s %-22s %-27s %-8s %-8s %-8s\n"
printf \
"\n\n*** Testing own and python's function with canonical absolute dirs\n\n"
printf "$format\n" \
"From Directory" "To Directory" "Rel. Path" "relPath" "relpath" "python"
IFS=
while read -r p; do
eval set -- $p
case $1 in '#'*|'') continue;; esac # Skip comments and empty lines
# q stores quoting character, use " if ' is used in path name
q="'"; case $1$2 in *"'"*) q='"';; esac
rPOk=passed rP=$(relPath "$1" "$2"); test "$rP" = "$3" || rPOk=$rP
rpOk=passed rp=$(relpath "$1" "$2"); test "$rp" = "$3" || rpOk=$rp
RPOk=passed
RP=$(python -c "import os.path; print os.path.relpath($q$2$q, $q$1$q)")
test "$RP" = "$3" || RPOk=$RP
printf \
"$format" "$q$1$q" "$q$2$q" "$q$3$q" "$q$rPOk$q" "$q$rpOk$q" "$q$RPOk$q"
done <<-"EOF"
# From directory To directory Expected relative path
'/' '/' '.'
'/usr' '/' '..'
'/usr/' '/' '..'
'/' '/usr' 'usr'
'/' '/usr/' 'usr'
'/usr' '/usr' '.'
'/usr/' '/usr' '.'
'/usr' '/usr/' '.'
'/usr/' '/usr/' '.'
'/u' '/usr' '../usr'
'/usr' '/u' '../u'
"/u'/dir" "/u'/dir" "."
"/u'" "/u'/dir" "dir"
"/u'/dir" "/u'" ".."
"/" "/u'/dir" "u'/dir"
"/u'/dir" "/" "../.."
"/u'" "/u'" "."
"/" "/u'" "u'"
"/u'" "/" ".."
'/u"/dir' '/u"/dir' '.'
'/u"' '/u"/dir' 'dir'
'/u"/dir' '/u"' '..'
'/' '/u"/dir' 'u"/dir'
'/u"/dir' '/' '../..'
'/u"' '/u"' '.'
'/' '/u"' 'u"'
'/u"' '/' '..'
'/u /dir' '/u /dir' '.'
'/u ' '/u /dir' 'dir'
'/u /dir' '/u ' '..'
'/' '/u /dir' 'u /dir'
'/u /dir' '/' '../..'
'/u ' '/u ' '.'
'/' '/u ' 'u '
'/u ' '/' '..'
'/u\n/dir' '/u\n/dir' '.'
'/u\n' '/u\n/dir' 'dir'
'/u\n/dir' '/u\n' '..'
'/' '/u\n/dir' 'u\n/dir'
'/u\n/dir' '/' '../..'
'/u\n' '/u\n' '.'
'/' '/u\n' 'u\n'
'/u\n' '/' '..'
'/ a b/å/⮀*/!' '/ a b/å/⮀/xäå/?' '../../⮀/xäå/?'
'/' '/A' 'A'
'/A' '/' '..'
'/ & / !/*/\\/E' '/' '../../../../..'
'/' '/ & / !/*/\\/E' ' & / !/*/\\/E'
'/ & / !/*/\\/E' '/ & / !/?/\\/E/F' '../../../?/\\/E/F'
'/X/Y' '/ & / !/C/\\/E/F' '../../ & / !/C/\\/E/F'
'/ & / !/C' '/A' '../../../A'
'/A / !/C' '/A /B' '../../B'
'/Â/ !/C' '/Â/ !/C' '.'
'/ & /B / C' '/ & /B / C/D' 'D'
'/ & / !/C' '/ & / !/C/\\/Ê' '\\/Ê'
'/Å/ !/C' '/Å/ !/D' '../D'
'/.A /*B/C' '/.A /*B/\\/E' '../\\/E'
'/ & / !/C' '/ & /D' '../../D'
'/ & / !/C' '/ & /\\/E' '../../\\/E'
'/ & / !/C' '/\\/E/F' '../../../\\/E/F'
'/home/p1/p2' '/home/p1/p3' '../p3'
'/home/p1/p2' '/home/p4/p5' '../../p4/p5'
'/home/p1/p2' '/work/p6/p7' '../../../work/p6/p7'
'/home/p1' '/work/p1/p2/p3/p4' '../../work/p1/p2/p3/p4'
'/home' '/work/p2/p3' '../work/p2/p3'
'/' '/work/p2/p3/p4' 'work/p2/p3/p4'
'/home/p1/p2' '/home/p1/p2/p3/p4' 'p3/p4'
'/home/p1/p2' '/home/p1/p2/p3' 'p3'
'/home/p1/p2' '/home/p1/p2' '.'
'/home/p1/p2' '/home/p1' '..'
'/home/p1/p2' '/home' '../..'
'/home/p1/p2' '/' '../../..'
'/home/p1/p2' '/work' '../../../work'
'/home/p1/p2' '/work/p1' '../../../work/p1'
'/home/p1/p2' '/work/p1/p2' '../../../work/p1/p2'
'/home/p1/p2' '/work/p1/p2/p3' '../../../work/p1/p2/p3'
'/home/p1/p2' '/work/p1/p2/p3/p4' '../../../work/p1/p2/p3/p4'
'/-' '/-' '.'
'/?' '/?' '.'
'/??' '/??' '.'
'/???' '/???' '.'
'/?*' '/?*' '.'
'/*' '/*' '.'
'/*' '/**' '../**'
'/*' '/***' '../***'
'/*.*' '/*.**' '../*.**'
'/*.???' '/*.??' '../*.??'
'/[]' '/[]' '.'
'/[a-z]*' '/[0-9]*' '../[0-9]*'
EOF
format="\t%-19s %-22s %-27s %-8s %-8s\n"
printf "\n\n*** Testing own and python's function with arbitrary dirs\n\n"
printf "$format\n" \
"From Directory" "To Directory" "Rel. Path" "relpath" "python"
IFS=
while read -r p; do
eval set -- $p
case $1 in '#'*|'') continue;; esac # Skip comments and empty lines
# q stores quoting character, use " if ' is used in path name
q="'"; case $1$2 in *"'"*) q='"';; esac
rpOk=passed rp=$(relpath "$1" "$2"); test "$rp" = "$3" || rpOk=$rp
RPOk=passed
RP=$(python -c "import os.path; print os.path.relpath($q$2$q, $q$1$q)")
test "$RP" = "$3" || RPOk=$RP
printf "$format" "$q$1$q" "$q$2$q" "$q$3$q" "$q$rpOk$q" "$q$RPOk$q"
done <<-"EOF"
# From directory To directory Expected relative path
'usr/p1/..//./p4' 'p3/../p1/p6/.././/p2' '../../p1/p2'
'./home/../../work' '..//././../dir///' '../../dir'
'home/p1/p2' 'home/p1/p3' '../p3'
'home/p1/p2' 'home/p4/p5' '../../p4/p5'
'home/p1/p2' 'work/p6/p7' '../../../work/p6/p7'
'home/p1' 'work/p1/p2/p3/p4' '../../work/p1/p2/p3/p4'
'home' 'work/p2/p3' '../work/p2/p3'
'.' 'work/p2/p3' 'work/p2/p3'
'home/p1/p2' 'home/p1/p2/p3/p4' 'p3/p4'
'home/p1/p2' 'home/p1/p2/p3' 'p3'
'home/p1/p2' 'home/p1/p2' '.'
'home/p1/p2' 'home/p1' '..'
'home/p1/p2' 'home' '../..'
'home/p1/p2' '.' '../../..'
'home/p1/p2' 'work' '../../../work'
'home/p1/p2' 'work/p1' '../../../work/p1'
'home/p1/p2' 'work/p1/p2' '../../../work/p1/p2'
'home/p1/p2' 'work/p1/p2/p3' '../../../work/p1/p2/p3'
'home/p1/p2' 'work/p1/p2/p3/p4' '../../../work/p1/p2/p3/p4'
EOF
#!/bin/bash
# both $1 and $2 are absolute paths
# returns $2 relative to $1
source=$1
target=$2
common_part=$source
back=
while [ "${target#$common_part}" = "${target}" ]; do
common_part=$(dirname $common_part)
back="../${back}"
done
echo ${back}${target#$common_part/}
这里的答案并不是每天都能用的。由于在纯bash中很难正确地做到这一点，我建议以下可靠的解决方案(类似于注释中的一个建议):
function relpath() {
python -c "import os,sys;print(os.path.relpath(*(sys.argv[1:])))" "$@";
}
然后，你可以得到基于当前目录的相对路径:
echo $(relpath somepath)
或者你可以指定路径相对于给定的目录:
echo $(relpath somepath /etc) # relative to /etc
一个缺点是这需要python，但是:
它在任何python >= 2.6中工作相同 它不要求文件或目录存在。 文件名可以包含更广泛的特殊字符。 例如，如果文件名包含 空格或其他特殊字符。 它是一个单行函数，不会使脚本混乱。
注意，包含basename或dirname的解决方案不一定更好，因为它们要求安装coreutils。如果有人有可靠而简单的纯bash解决方案(而不是令人费解的好奇心)，我会感到惊讶。
可悲的是，Mark Rushakoff的答案(现在删除了-它引用了这里的代码)在适应时似乎不能正确工作:
source=/home/part2/part3/part4
target=/work/proj1/proj2
注释中概述的思想可以经过改进，使其在大多数情况下正确工作。我假设脚本有一个源参数(您所在的位置)和一个目标参数(您想要到达的位置)，这两个参数要么是绝对路径名，要么是相对路径名。如果一个是绝对的，另一个是相对的，最简单的方法是用当前工作目录作为相对名称的前缀——但是下面的代码没有这样做。
当心
下面的代码接近正确工作，但不是很正确。
丹尼斯·威廉姆森(Dennis Williamson)的评论中提到了一个问题。 还有一个问题，这种纯文本的路径名处理，你可能会被奇怪的符号链接搞得一团糟。 该代码不处理'xyz/./pqr'等路径中的零散'点'。 该代码不处理'xyz/../pqr'等路径中的流浪'双点'。 简单地说:代码没有删除前导'。/'从路径。
Dennis的代码更好，因为它修复了1和5，但也有相同的问题2,3,4。 因此，请使用Dennis的代码(并在此之前对其进行投票)。
注意:POSIX提供了一个系统调用realpath()来解析路径名，这样路径名中就没有符号链接了。将其应用于输入名称，然后使用Dennis的代码每次都会给出正确的答案。编写包装realpath()的C代码很简单——我已经做过了——但我不知道有什么标准实用程序可以这样做。)
为此，我发现Perl比shell更容易使用，尽管bash对数组有很好的支持，并且可能也可以做到这一点——这是读者的练习。因此，给定两个兼容的名称，将它们分别分解为组件:
Set the relative path to empty. While the components are the same, skip to the next. When corresponding components are different or there are no more components for one path: If there are no remaining source components and the relative path is empty, add "." to the start. For each remaining source component, prefix the relative path with "../". If there are no remaining target components and the relative path is empty, add "." to the start. For each remaining target component, add the component to the end of the path after a slash.
因此:
#!/bin/perl -w
use strict;
# Should fettle the arguments if one is absolute and one relative:
# Oops - missing functionality!
# Split!
my(@source) = split '/', $ARGV[0];
my(@target) = split '/', $ARGV[1];
my $count = scalar(@source);
$count = scalar(@target) if (scalar(@target) < $count);
my $relpath = "";
my $i;
for ($i = 0; $i < $count; $i++)
{
last if $source[$i] ne $target[$i];
}
$relpath = "." if ($i >= scalar(@source) && $relpath eq "");
for (my $s = $i; $s < scalar(@source); $s++)
{
$relpath = "../$relpath";
}
$relpath = "." if ($i >= scalar(@target) && $relpath eq "");
for (my $t = $i; $t < scalar(@target); $t++)
{
$relpath .= "/$target[$t]";
}
# Clean up result (remove double slash, trailing slash, trailing slash-dot).
$relpath =~ s%//%/%;
$relpath =~ s%/$%%;
$relpath =~ s%/\.$%%;
print "source = $ARGV[0]\n";
print "target = $ARGV[1]\n";
print "relpath = $relpath\n";
测试脚本(方括号包含一个空格和一个制表符):
sed 's/#.*//;/^[ ]*$/d' <<! |
/home/part1/part2 /home/part1/part3
/home/part1/part2 /home/part4/part5
/home/part1/part2 /work/part6/part7
/home/part1 /work/part1/part2/part3/part4
/home /work/part2/part3
/ /work/part2/part3/part4
/home/part1/part2 /home/part1/part2/part3/part4
/home/part1/part2 /home/part1/part2/part3
/home/part1/part2 /home/part1/part2
/home/part1/part2 /home/part1
/home/part1/part2 /home
/home/part1/part2 /
/home/part1/part2 /work
/home/part1/part2 /work/part1
/home/part1/part2 /work/part1/part2
/home/part1/part2 /work/part1/part2/part3
/home/part1/part2 /work/part1/part2/part3/part4
home/part1/part2 home/part1/part3
home/part1/part2 home/part4/part5
home/part1/part2 work/part6/part7
home/part1 work/part1/part2/part3/part4
home work/part2/part3
. work/part2/part3
home/part1/part2 home/part1/part2/part3/part4
home/part1/part2 home/part1/part2/part3
home/part1/part2 home/part1/part2
home/part1/part2 home/part1
home/part1/part2 home
home/part1/part2 .
home/part1/part2 work
home/part1/part2 work/part1
home/part1/part2 work/part1/part2
home/part1/part2 work/part1/part2/part3
home/part1/part2 work/part1/part2/part3/part4
!
while read source target
do
perl relpath.pl $source $target
echo
done
测试脚本的输出:
source = /home/part1/part2
target = /home/part1/part3
relpath = ../part3
source = /home/part1/part2
target = /home/part4/part5
relpath = ../../part4/part5
source = /home/part1/part2
target = /work/part6/part7
relpath = ../../../work/part6/part7
source = /home/part1
target = /work/part1/part2/part3/part4
relpath = ../../work/part1/part2/part3/part4
source = /home
target = /work/part2/part3
relpath = ../work/part2/part3
source = /
target = /work/part2/part3/part4
relpath = ./work/part2/part3/part4
source = /home/part1/part2
target = /home/part1/part2/part3/part4
relpath = ./part3/part4
source = /home/part1/part2
target = /home/part1/part2/part3
relpath = ./part3
source = /home/part1/part2
target = /home/part1/part2
relpath = .
source = /home/part1/part2
target = /home/part1
relpath = ..
source = /home/part1/part2
target = /home
relpath = ../..
source = /home/part1/part2
target = /
relpath = ../../../..
source = /home/part1/part2
target = /work
relpath = ../../../work
source = /home/part1/part2
target = /work/part1
relpath = ../../../work/part1
source = /home/part1/part2
target = /work/part1/part2
relpath = ../../../work/part1/part2
source = /home/part1/part2
target = /work/part1/part2/part3
relpath = ../../../work/part1/part2/part3
source = /home/part1/part2
target = /work/part1/part2/part3/part4
relpath = ../../../work/part1/part2/part3/part4
source = home/part1/part2
target = home/part1/part3
relpath = ../part3
source = home/part1/part2
target = home/part4/part5
relpath = ../../part4/part5
source = home/part1/part2
target = work/part6/part7
relpath = ../../../work/part6/part7
source = home/part1
target = work/part1/part2/part3/part4
relpath = ../../work/part1/part2/part3/part4
source = home
target = work/part2/part3
relpath = ../work/part2/part3
source = .
target = work/part2/part3
relpath = ../work/part2/part3
source = home/part1/part2
target = home/part1/part2/part3/part4
relpath = ./part3/part4
source = home/part1/part2
target = home/part1/part2/part3
relpath = ./part3
source = home/part1/part2
target = home/part1/part2
relpath = .
source = home/part1/part2
target = home/part1
relpath = ..
source = home/part1/part2
target = home
relpath = ../..
source = home/part1/part2
target = .
relpath = ../../..
source = home/part1/part2
target = work
relpath = ../../../work
source = home/part1/part2
target = work/part1
relpath = ../../../work/part1
source = home/part1/part2
target = work/part1/part2
relpath = ../../../work/part1/part2
source = home/part1/part2
target = work/part1/part2/part3
relpath = ../../../work/part1/part2/part3
source = home/part1/part2
target = work/part1/part2/part3/part4
relpath = ../../../work/part1/part2/part3/part4
面对奇怪的输入，这个Perl脚本在Unix上运行得相当彻底(它没有考虑Windows路径名的所有复杂性)。它使用模块Cwd及其函数realpath解析存在的名称的真实路径，并对不存在的路径进行文本分析。在所有情况下，除了一种情况，它产生的输出都与Dennis的脚本相同。越轨的情况是:
source = home/part1/part2
target = .
relpath1 = ../../..
relpath2 = ../../../.
这两个结果是等价的，只是不完全相同。(输出来自测试脚本的一个轻微修改版本——下面的Perl脚本只是输出答案，而不是像上面的脚本那样输出输入和答案。)现在，我应该排除无效的答案吗?也许……
#!/bin/perl -w
# Based loosely on code from: http://unix.derkeiler.com/Newsgroups/comp.unix.shell/2005-10/1256.html
# Via: http://stackoverflow.com/questions/2564634
use strict;
die "Usage: $0 from to\n" if scalar @ARGV != 2;
use Cwd qw(realpath getcwd);
my $pwd;
my $verbose = 0;
# Fettle filename so it is absolute.
# Deals with '//', '/./' and '/../' notations, plus symlinks.
# The realpath() function does the hard work if the path exists.
# For non-existent paths, the code does a purely textual hack.
sub resolve
{
my($name) = @_;
my($path) = realpath($name);
if (!defined $path)
{
# Path does not exist - do the best we can with lexical analysis
# Assume Unix - not dealing with Windows.
$path = $name;
if ($name !~ m%^/%)
{
$pwd = getcwd if !defined $pwd;
$path = "$pwd/$path";
}
$path =~ s%//+%/%g; # Not UNC paths.
$path =~ s%/$%%; # No trailing /
$path =~ s%/\./%/%g; # No embedded /./
# Try to eliminate /../abc/
$path =~ s%/\.\./(?:[^/]+)(/|$)%$1%g;
$path =~ s%/\.$%%; # No trailing /.
$path =~ s%^\./%%; # No leading ./
# What happens with . and / as inputs?
}
return($path);
}
sub print_result
{
my($source, $target, $relpath) = @_;
if ($verbose)
{
print "source = $ARGV[0]\n";
print "target = $ARGV[1]\n";
print "relpath = $relpath\n";
}
else
{
print "$relpath\n";
}
exit 0;
}
my($source) = resolve($ARGV[0]);
my($target) = resolve($ARGV[1]);
print_result($source, $target, ".") if ($source eq $target);
# Split!
my(@source) = split '/', $source;
my(@target) = split '/', $target;
my $count = scalar(@source);
$count = scalar(@target) if (scalar(@target) < $count);
my $relpath = "";
my $i;
# Both paths are absolute; Perl splits an empty field 0.
for ($i = 1; $i < $count; $i++)
{
last if $source[$i] ne $target[$i];
}
for (my $s = $i; $s < scalar(@source); $s++)
{
$relpath = "$relpath/" if ($s > $i);
$relpath = "$relpath..";
}
for (my $t = $i; $t < scalar(@target); $t++)
{
$relpath = "$relpath/" if ($relpath ne "");
$relpath = "$relpath$target[$t]";
}
print_result($source, $target, $relpath);
该脚本仅对绝对路径或没有绝对路径的相对路径的输入提供正确的结果。或者. .:
#!/bin/bash
# usage: relpath from to
if [[ "$1" == "$2" ]]
then
echo "."
exit
fi
IFS="/"
current=($1)
absolute=($2)
abssize=${#absolute[@]}
cursize=${#current[@]}
while [[ ${absolute[level]} == ${current[level]} ]]
do
(( level++ ))
if (( level > abssize || level > cursize ))
then
break
fi
done
for ((i = level; i < cursize; i++))
do
if ((i > level))
then
newpath=$newpath"/"
fi
newpath=$newpath".."
done
for ((i = level; i < abssize; i++))
do
if [[ -n $newpath ]]
then
newpath=$newpath"/"
fi
newpath=$newpath${absolute[i]}
done
echo "$newpath"
