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 '$result'"
fi
done
# vi: set tabstop=3 shiftwidth=3 expandtab fileformat=unix :
其他回答
下面是一个shell脚本，它可以在不调用其他程序的情况下完成:
#! /bin/env bash
#bash script to find the relative path between two directories
mydir=${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
$ python -c "import os.path; print os.path.relpath('/foo/bar', '/foo/baz/foo')"
给:
../../bar
#!/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#$common_part/}
我的解决方案:
computeRelativePath()
{
Source=$(readlink -f ${1})
Target=$(readlink -f ${2})
local OLDIFS=$IFS
IFS="/"
local SourceDirectoryArray=($Source)
local TargetDirectoryArray=($Target)
local SourceArrayLength=$(echo ${SourceDirectoryArray[@]} | wc -w)
local TargetArrayLength=$(echo ${TargetDirectoryArray[@]} | wc -w)
local Length
test $SourceArrayLength -gt $TargetArrayLength && Length=$SourceArrayLength || Length=$TargetArrayLength
local Result=""
local AppendToEnd=""
IFS=$OLDIFS
local i
for ((i = 0; i <= $Length + 1 ; i++ ))
do
if [ "${SourceDirectoryArray[$i]}" = "${TargetDirectoryArray[$i]}" ]
then
continue
elif [ "${SourceDirectoryArray[$i]}" != "" ] && [ "${TargetDirectoryArray[$i]}" != "" ]
then
AppendToEnd="${AppendToEnd}${TargetDirectoryArray[${i}]}/"
Result="${Result}../"
elif [ "${SourceDirectoryArray[$i]}" = "" ]
then
Result="${Result}${TargetDirectoryArray[${i}]}/"
else
Result="${Result}../"
fi
done
Result="${Result}${AppendToEnd}"
echo $Result
}
#!/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
