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
我需要这样的东西，但它也解决了符号链接。我发现pwd有一个-P标志用于此目的。附加了我的脚本的一个片段。它在shell脚本的函数中，因此是$1和$2。结果值是从START_ABS到END_ABS的相对路径，位于UPDIRS变量中。为了执行pwd -P，将脚本cd放入每个参数目录，这也意味着将处理相对路径参数。干杯,吉姆
SAVE_DIR="$PWD"
cd "$1"
START_ABS=`pwd -P`
cd "$SAVE_DIR"
cd "$2"
END_ABS=`pwd -P`
START_WORK="$START_ABS"
UPDIRS=""
while test -n "${START_WORK}" -a "${END_ABS/#${START_WORK}}" '==' "$END_ABS";
do
START_WORK=`dirname "$START_WORK"`"/"
UPDIRS=${UPDIRS}"../"
done
UPDIRS="$UPDIRS${END_ABS/#${START_WORK}}"
cd "$SAVE_DIR"
其他回答
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'")')
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
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
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
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