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'","'$current'")')
其他回答
test.sh:
#!/bin/bash
cd /home/ubuntu
touch blah
TEST=/home/ubuntu/.//blah
echo TEST=$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
#!/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
使用GNU coreutils 8.23中的realpath是最简单的，我认为:
$ realpath --relative-to="$file1" "$file2"
例如:
$ realpath --relative-to=/usr/bin/nmap /tmp/testing
../../../tmp/testing
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
这个脚本只对路径名有效。它不需要任何文件存在。如果传递的路径不是绝对的，那么行为就有点不寻常，但是如果两条路径都是相对的，那么应该能正常工作。
我只在OS X上测试过，所以可能不太便携。
#!/bin/bash
set -e
declare SCRIPT_NAME="$(basename $0)"
function usage {
echo "Usage: $SCRIPT_NAME <base path> <target file>"
echo " Outputs <target file> relative to <base path>"
exit 1
}
if [ $# -lt 2 ]; then usage; fi
declare base=$1
declare target=$2
declare -a base_part=()
declare -a target_part=()
#Split path elements & canonicalize
OFS="$IFS"; IFS='/'
bpl=0;
for bp in $base; do
case "$bp" in
".");;
"..") let "bpl=$bpl-1" ;;
*) base_part[${bpl}]="$bp" ; let "bpl=$bpl+1";;
esac
done
tpl=0;
for tp in $target; do
case "$tp" in
".");;
"..") let "tpl=$tpl-1" ;;
*) target_part[${tpl}]="$tp" ; let "tpl=$tpl+1";;
esac
done
IFS="$OFS"
#Count common prefix
common=0
for (( i=0 ; i<$bpl ; i++ )); do
if [ "${base_part[$i]}" = "${target_part[$common]}" ] ; then
let "common=$common+1"
else
break
fi
done
#Compute number of directories up
let "updir=$bpl-$common" || updir=0 #if the expression is zero, 'let' fails
#trivial case (after canonical decomposition)
if [ $updir -eq 0 ]; then
echo .
exit
fi
#Print updirs
for (( i=0 ; i<$updir ; i++ )); do
echo -n ../
done
#Print remaining path
for (( i=$common ; i<$tpl ; i++ )); do
if [ $i -ne $common ]; then
echo -n "/"
fi
if [ "" != "${target_part[$i]}" ] ; then
echo -n "${target_part[$i]}"
fi
done
#One last newline
echo
