带有 OS X 的 Bash 脚本绝对路径

Question

我正在尝试获取 OS X 上当前正在运行的脚本的绝对路径。

我看到很多人回复readlink -f $0。然而，由于 OS X 的 readlink 与 BSD 相同，所以它不起作用（它适用于 GNU 的版本）。

是否有开箱即用的解决方案？

Answer 1

有一个realpath() C 函数可以完成这项工作，但我在命令行上看不到任何可用的东西。这是一个快速而肮脏的替换：

#!/bin/bash

realpath() {
    [[ $1 = /* ]] && echo "$1" || echo "$PWD/${1#./}"
}

realpath "$0"

如果路径以/ 开头，则会逐字打印路径。如果不是，它必须是相对路径，所以它会将$PWD 放在前面。 #./ 部分从$1 的前面剥离./。

Answer 2

出于以下几个原因，我发现答案有点欠缺：
特别是，它们不能解析多个级别的符号链接，而且它们非常“Bash-y”。

虽然最初的问题确实明确要求“Bash 脚本”，但它也提到了 Mac OS X 的类似 BSD、非 GNU readlink。

所以这里尝试了一些合理的可移植性（我已经用 bash 作为 'sh' 和破折号对其进行了检查），解析任意数量的符号链接；它还应该与路径中的空格一起使用。

此答案之前已编辑，重新添加了 local bashism。这个答案的重点是一个可移植的 POSIX 解决方案。我已经对其进行了编辑，以通过将其更改为子shell函数而不是内联函数来解决变量范围。请不要编辑。

#!/bin/sh
realpath() (
  OURPWD=$PWD
  cd "$(dirname "$1")"
  LINK=$(readlink "$(basename "$1")")
  while [ "$LINK" ]; do
    cd "$(dirname "$LINK")"
    LINK=$(readlink "$(basename "$1")")
  done
  REALPATH="$PWD/$(basename "$1")"
  cd "$OURPWD"
  echo "$REALPATH"
)
realpath "$@"

希望对某人有用。

Answer 3

正如您在上面看到的，我在大约 6 个月前对此进行了拍摄。我完全 忘了它，直到我发现自己再次需要类似的东西。我曾是 完全震惊看到它是多么简陋；我一直在教 我自己花了大约一年的时间进行非常密集的编码，但我经常觉得 也许在最糟糕的时候我什么都没学到。

我会删除上面的“解决方案”，但我真的很喜欢它作为记录 在过去的几个月里，我真的学到了多少。

但我离题了。昨晚我坐下来把这一切都解决了。中的解释 cmets应该足够了。如果您想跟踪副本，我将继续 继续工作，you can follow this gist. 这可能满足您的需求。

#!/bin/sh # dash bash ksh # !zsh (issues). G. Nixon, 12/2013. Public domain.

## 'linkread' or 'fullpath' or (you choose) is a little tool to recursively
## dereference symbolic links (ala 'readlink') until the originating file
## is found. This is effectively the same function provided in stdlib.h as
## 'realpath' and on the command line in GNU 'readlink -f'.

## Neither of these tools, however, are particularly accessible on the many
## systems that do not have the GNU implementation of readlink, nor ship
## with a system compiler (not to mention the requisite knowledge of C).

## This script is written with portability and (to the extent possible, speed)
## in mind, hence the use of printf for echo and case statements where they
## can be substituded for test, though I've had to scale back a bit on that.

## It is (to the best of my knowledge) written in standard POSIX shell, and
## has been tested with bash-as-bin-sh, dash, and ksh93. zsh seems to have
## issues with it, though I'm not sure why; so probably best to avoid for now.

## Particularly useful (in fact, the reason I wrote this) is the fact that
## it can be used within a shell script to find the path of the script itself.
## (I am sure the shell knows this already; but most likely for the sake of
## security it is not made readily available. The implementation of "$0"
## specificies that the $0 must be the location of **last** symbolic link in
## a chain, or wherever it resides in the path.) This can be used for some
## ...interesting things, like self-duplicating and self-modifiying scripts.

## Currently supported are three errors: whether the file specified exists
## (ala ENOENT), whether its target exists/is accessible; and the special
## case of when a sybolic link references itself "foo -> foo": a common error
## for beginners, since 'ln' does not produce an error if the order of link
## and target are reversed on the command line. (See POSIX signal ELOOP.)

## It would probably be rather simple to write to use this as a basis for
## a pure shell implementation of the 'symlinks' util included with Linux.

## As an aside, the amount of code below **completely** belies the amount
## effort it took to get this right -- but I guess that's coding for you.

##===-------------------------------------------------------------------===##

for argv; do :; done # Last parameter on command line, for options parsing.

## Error messages. Use functions so that we can sub in when the error occurs.

recurses(){ printf "Self-referential:\n\t$argv ->\n\t$argv\n" ;}
dangling(){ printf "Broken symlink:\n\t$argv ->\n\t"$(readlink "$argv")"\n" ;}
errnoent(){ printf "No such file: "$@"\n" ;} # Borrow a horrible signal name.

# Probably best not to install as 'pathfull', if you can avoid it.

pathfull(){ cd "$(dirname "$@")"; link="$(readlink "$(basename "$@")")"

## 'test and 'ls' report different status for bad symlinks, so we use this.

 if [ ! -e "$@" ]; then if $(ls -d "$@" 2>/dev/null) 2>/dev/null;  then
    errnoent 1>&2; exit 1; elif [ ! -e "$@" -a "$link" = "$@" ];   then
    recurses 1>&2; exit 1; elif [ ! -e "$@" ] && [ ! -z "$link" ]; then
    dangling 1>&2; exit 1; fi
 fi

## Not a link, but there might be one in the path, so 'cd' and 'pwd'.

 if [ -z "$link" ]; then if [ "$(dirname "$@" | cut -c1)" = '/' ]; then
   printf "$@\n"; exit 0; else printf "$(pwd)/$(basename "$@")\n"; fi; exit 0
 fi

## Walk the symlinks back to the origin. Calls itself recursivly as needed.

 while [ "$link" ]; do
   cd "$(dirname "$link")"; newlink="$(readlink "$(basename "$link")")"
   case "$newlink" in
    "$link") dangling 1>&2 && exit 1                                       ;;
         '') printf "$(pwd)/$(basename "$link")\n"; exit 0                 ;;
          *) link="$newlink" && pathfull "$link"                           ;;
   esac
 done
 printf "$(pwd)/$(basename "$newlink")\n"
}

## Demo. Install somewhere deep in the filesystem, then symlink somewhere 
## else, symlink again (maybe with a different name) elsewhere, and link
## back into the directory you started in (or something.) The absolute path
## of the script will always be reported in the usage, along with "$0".

if [ -z "$argv" ]; then scriptname="$(pathfull "$0")"

# Yay ANSI l33t codes! Fancy.
 printf "\n\033[3mfrom/as: \033[4m$0\033[0m\n\n\033[1mUSAGE:\033[0m   "
 printf "\033[4m$scriptname\033[24m [ link | file | dir ]\n\n         "
 printf "Recursive readlink for the authoritative file, symlink after "
 printf "symlink.\n\n\n         \033[4m$scriptname\033[24m\n\n        "
 printf " From within an invocation of a script, locate the script's "
 printf "own file\n         (no matter where it has been linked or "
 printf "from where it is being called).\n\n"

else pathfull "$@"
fi

Answer 4

这三个简单的步骤将解决这个问题和许多其他 OS X 问题：

1. 安装Homebrew
2. brew install coreutils
3. grealpath .

(3) 可以改为 realpath，见 (2) 输出

Answer 5

我一直在寻找在系统配置脚本中使用的解决方案，即在安装 Homebrew 之前运行。由于缺乏合适的解决方案，我只能将任务转移到跨平台语言，例如 Perl：

script_abspath=$(perl -e 'use Cwd "abs_path"; print abs_path(@ARGV[0])' -- "$0")

更多时候我们真正想要的是包含目录：

here=$(perl -e 'use File::Basename; use Cwd "abs_path"; print dirname(abs_path(@ARGV[0]));' -- "$0")

Answer 6

使用 Python 获取：

#!/usr/bin/env python
import os
import sys

print(os.path.realpath(sys.argv[1]))

Answer 7

Python 解决方案对命令行更友好的变体：

python -c 'import os, sys; print(os.path.realpath(sys.argv[1]))' ./my/path

Answer 8

因为有一个realpath，正如其他人指出的那样：

// realpath.c
#include <stdio.h>
#include <stdlib.h>

int main (int argc, char* argv[])
{
  if (argc > 1) {
    for (int argIter = 1; argIter < argc; ++argIter) {
      char *resolved_path_buffer = NULL;
      char *result = realpath(argv[argIter], resolved_path_buffer);

      puts(result);

      if (result != NULL) {
        free(result);
      }
    }
  }

  return 0;
}

生成文件：

#Makefile
OBJ = realpath.o

%.o: %.c
      $(CC) -c -o $@ $< $(CFLAGS)

realpath: $(OBJ)
      gcc -o $@ $^ $(CFLAGS)

然后使用make 编译并放入软链接：
ln -s $(pwd)/realpath /usr/local/bin/realpath

Answer 9

Mac OS X 的真实路径

realpath() {
    path=`eval echo "$1"`
    folder=$(dirname "$path")
    echo $(cd "$folder"; pwd)/$(basename "$path"); 
}

相关路径示例：

realpath "../scripts/test.sh"

主文件夹示例

realpath "~/Test/../Test/scripts/test.sh"

Answer 10

根据与评论者的交流，我同意这是非常困难的，并且没有简单的方法来实现与 Ubuntu 完全相同的真实路径。

但以下版本，可以处理极端情况最佳答案不能满足我在 macbook 上的日常需求。将此代码放入您的 ~/.bashrc 并记住：

• arg 只能是 1 个文件或目录，不能是通配符
• 目录或文件名中没有空格
• 至少文件或目录的父目录存在
• 请随意使用。 ../东西，这些是安全的

---

    # 1. if is a dir, try cd and pwd
    # 2. if is a file, try cd its parent and concat dir+file
    realpath() {
     [ "$1" = "" ] && return 1

     dir=`dirname "$1"`
     file=`basename "$1"`

     last=`pwd`

     [ -d "$dir" ] && cd $dir || return 1
     if [ -d "$file" ];
     then
       # case 1
       cd $file && pwd || return 1
     else
       # case 2
       echo `pwd`/$file | sed 's/\/\//\//g'
     fi

     cd $last
    }

Answer 11

在 macOS 上，我发现的唯一可靠处理符号链接的解决方案是使用 realpath。因为这需要brew install coreutils，所以我只是自动化了这一步。我的实现如下所示：

#!/usr/bin/env bash

set -e

if ! which realpath >&/dev/null; then
  if ! which brew >&/dev/null; then
    msg="ERROR: This script requires brew. See https://brew.sh for installation instructions."
    echo "$(tput setaf 1)$msg$(tput sgr0)" >&2
    exit 1
  fi
  echo "Installing coreutils/realpath"
  brew install coreutils >&/dev/null
fi

thisDir=$( dirname "`realpath "$0"`" )
echo "This script is run from \"$thisDir\""

如果他们没有安装brew，则会出现此错误，但您也可以直接安装它。我只是对自动化一些从网上卷曲任意 ruby​​ 代码的东西感到不舒服。

请注意，这是 Oleg Mikheev 的 answer 的自动变体。

---

一项重要的测试

对这些解决方案的一个很好的测试是：

1. 将代码放在某个脚本文件中
2. 在另一个目录中，符号链接 (ln -s) 到该文件
3. 从该符号链接运行脚本

解决方案是否取消引用符号链接，并为您提供原始目录？如果是这样，它的工作原理。

Answer 12

这似乎适用于 OSX，不需要任何二进制文件，并且被拉取 from here

function normpath() {
  # Remove all /./ sequences.
  local path=${1//\/.\//\/}

  # Remove dir/.. sequences.
  while [[ $path =~ ([^/][^/]*/\.\./) ]]; do
    path=${path/${BASH_REMATCH[0]}/}
  done
  echo $path
}

Answer 13

我喜欢这个：

#!/usr/bin/env bash
function realpath() {
    local _X="$PWD"
    local _LNK=$1
    cd "$(dirname "$_LNK")"
    if [ -h "$_LNK" ]; then
        _LNK="$(readlink "$_LNK")"
        cd "$(dirname "$_LNK")"
    fi
    echo "$PWD/$(basename "$_LNK")"
    cd "$_X"
}

Answer 14

abs_path () {    
   echo "$(cd $(dirname "$1");pwd)/$(basename "$1")"
}

dirname 将给出/path/to/file 的目录名称，即/path/to。

cd /path/to; pwd 确保路径是绝对的。

basename 将只给出/path/to/file 中的文件名，即file。

Answer 15

我需要在 OS X 上替换 realpath，它可以在带有符号链接和父引用的路径上正确运行就像 readlink -f 一样。这包括在解析父引用之前解析路径中的符号链接；例如如果您已经安装了自制软件coreutils 瓶，则运行：

$ ln -s /var/log/cups /tmp/linkeddir  # symlink to another directory
$ greadlink -f /tmp/linkeddir/..      # canonical path of the link parent
/private/var/log

请注意，readlink -f 已解析 /tmp/linkeddir 在解析 .. 父目录引用之前。当然，Mac 上也没有readlink -f。

因此，作为 realpath 的 bash 实现的一部分，我在 Bash 3.2 中重新实现了 GNUlib canonicalize_filename_mode(path, CAN_ALL_BUT_LAST) function call does；这也是 GNU readlink -f 进行的函数调用：

# shellcheck shell=bash
set -euo pipefail

_contains() {
    # return true if first argument is present in the other arguments
    local elem value

    value="$1"
    shift

    for elem in "$@"; do 
        if [[ $elem == "$value" ]]; then
            return 0
        fi
    done
    return 1
}

_canonicalize_filename_mode() {
    # resolve any symlink targets, GNU readlink -f style
    # where every path component except the last should exist and is
    # resolved if it is a symlink. This is essentially a re-implementation
    # of canonicalize_filename_mode(path, CAN_ALL_BUT_LAST).
    # takes the path to canonicalize as first argument

    local path result component seen
    seen=()
    path="$1"
    result="/"
    if [[ $path != /* ]]; then  # add in current working dir if relative
        result="$PWD"
    fi
    while [[ -n $path ]]; do
        component="${path%%/*}"
        case "$component" in
            '') # empty because it started with /
                path="${path:1}" ;;
            .)  # ./ current directory, do nothing
                path="${path:1}" ;;
            ..) # ../ parent directory
                if [[ $result != "/" ]]; then  # not at the root?
                    result="${result%/*}"      # then remove one element from the path
                fi
                path="${path:2}" ;;
            *)
                # add this component to the result, remove from path
                if [[ $result != */ ]]; then
                    result="$result/"
                fi
                result="$result$component"
                path="${path:${#component}}"
                # element must exist, unless this is the final component
                if [[ $path =~ [^/] && ! -e $result ]]; then
                    echo "$1: No such file or directory" >&2
                    return 1
                fi
                # if the result is a link, prefix it to the path, to continue resolving
                if [[ -L $result ]]; then
                    if _contains "$result" "${seen[@]+"${seen[@]}"}"; then
                        # we've seen this link before, abort
                        echo "$1: Too many levels of symbolic links" >&2
                        return 1
                    fi
                    seen+=("$result")
                    path="$(readlink "$result")$path"
                    if [[ $path = /* ]]; then
                        # if the link is absolute, restart the result from /
                        result="/"
                    elif [[ $result != "/" ]]; then
                        # otherwise remove the basename of the link from the result
                        result="${result%/*}"
                    fi
                elif [[ $path =~ [^/] && ! -d $result ]]; then
                    # otherwise all but the last element must be a dir
                    echo "$1: Not a directory" >&2
                    return 1
                fi
                ;;
        esac
    done
    echo "$result"
}

它包括循环符号链接检测，如果相同（中间）路径出现两次则退出。

如果你只需要readlink -f，那么你可以使用上面的：

readlink() {
    if [[ $1 != -f ]]; then  # poor-man's option parsing
        # delegate to the standard readlink command
        command readlink "$@"
        return
    fi

    local path result seenerr
    shift
    seenerr=
    for path in "$@"; do
        # by default readlink suppresses error messages
        if ! result=$(_canonicalize_filename_mode "$path" 2>/dev/null); then
            seenerr=1
            continue
        fi
        echo "$result"
    done
    if [[ $seenerr ]]; then
        return 1;
    fi
}

对于realpath，我还需要--relative-to 和--relative-base 支持，它们在规范化后为您提供相对路径：

_realpath() {
    # GNU realpath replacement for bash 3.2 (OS X)
    # accepts --relative-to= and --relative-base options
    # and produces canonical (relative or absolute) paths for each
    # argument on stdout, errors on stderr, and returns 0 on success
    # and 1 if at least 1 path triggered an error.

    local relative_to relative_base seenerr path

    relative_to=
    relative_base=
    seenerr=

    while [[ $# -gt 0 ]]; do
        case $1 in
            "--relative-to="*)
                relative_to=$(_canonicalize_filename_mode "${1#*=}")
                shift 1;;
            "--relative-base="*)
                relative_base=$(_canonicalize_filename_mode "${1#*=}")
                shift 1;;
            *)
                break;;
        esac
    done

    if [[
        -n $relative_to
        && -n $relative_base
        && ${relative_to#${relative_base}/} == "$relative_to"
    ]]; then
        # relative_to is not a subdir of relative_base -> ignore both
        relative_to=
        relative_base=
    elif [[ -z $relative_to && -n $relative_base ]]; then
        # if relative_to has not been set but relative_base has, then
        # set relative_to from relative_base, simplifies logic later on
        relative_to="$relative_base"
    fi

    for path in "$@"; do
        if ! real=$(_canonicalize_filename_mode "$path"); then
            seenerr=1
            continue
        fi

        # make path relative if so required
        if [[
            -n $relative_to
            && ( # path must not be outside relative_base to be made relative
                -z $relative_base || ${real#${relative_base}/} != "$real"
            )
        ]]; then
            local common_part parentrefs

            common_part="$relative_to"
            parentrefs=
            while [[ ${real#${common_part}/} == "$real" ]]; do
                common_part="$(dirname "$common_part")"
                parentrefs="..${parentrefs:+/$parentrefs}"
            done

            if [[ $common_part != "/" ]]; then
                real="${parentrefs:+${parentrefs}/}${real#${common_part}/}"
            fi
        fi

        echo "$real"
    done
    if [[ $seenerr ]]; then
        return 1
    fi
}

if ! command -v realpath > /dev/null 2>&1; then
    # realpath is not available on OSX unless you install the `coreutils` brew
    realpath() { _realpath "$@"; }
fi

我在Code Review request for this code 中包含了单元测试。

Answer 16

我检查了每个答案，但错过了 Jason S 2016 年 7 月 14 日 3:12 的最佳答案（恕我直言），离开了评论字段。

所以就在这里，以防像我这样的人倾向于检查答案并且没有时间检查每一个 cmets：

$( cd "$(dirname "$0")" ; pwd -P )

帮助：

NAME
     pwd -- return working directory name

SYNOPSIS
     pwd [-L | -P]

DESCRIPTION
     The pwd utility writes the absolute pathname of the current working
     directory to the standard output.

     Some shells may provide a builtin pwd command which is similar or identi-
     cal to this utility.  Consult the builtin(1) manual page.

     The options are as follows:

     -L      Display the logical current working directory.

     -P      Display the physical current working directory (all symbolic
             links resolved).