我相信我得到了这个一个,我迟到了派对,但我认为有些人会欣赏它在这里,如果他们通过这个条纹。

#!/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

这里是JavaScript(即Node.js)的替代方案:

baseDirRelative=$(dirname "$0")
baseDir=$(node -e "console.log(require('path').resolve('$baseDirRelative'))") # Get absolute path using Node.js

echo $baseDir

我通常做:

LIBDIR=$(dirname "$(readlink -f "$(type -P $0 || echo $0)")")
source $LIBDIR/lib.sh

下面是一个命令,在Bash或zsh下工作,以及是否单独执行或源:

[ -n "$ZSH_VERSION" ] && this_dir=$(dirname "${(%):-%x}") \
    || this_dir=$(dirname "${BASH_SOURCE[0]:-$0}")

它是如何工作的

Fallback 替代操作员:

% x=ok
% echo "${x}"
ok

% echo "${x:-fallback}"
ok

% x=
% echo "${x:-fallback}"
fallback

% y=yvalue
% echo "${x:-$y}"
yvalue

此分類上一篇: %x prompt escape code

接下来,我们将引入即时逃避代码,一个 zsh-only 功能. 在 zsh 中, %x 将扩展到文件的路径,但通常只有在进行即时行扩展时。

% cat apath/test.sh
fpath=%x
echo "${(%)fpath}"

% source apath/test.sh
apath/test.sh

% cd apath
% source test.sh
test.sh

% cat test.sh
echo "${(%):-%x}"

% source test.sh
test.sh

请注意,我们通常会把变量名称放在(%)和(%)之间,但我们留下了白色。

我们可能已经使用打印 -P %x 以获得相同的文件路径,有更少的黑客,但在我们的情况下,我们需要将其作为一个论点转到一个字符串,这将需要一个开始一个新的字符串的顶部:

% cat apath/test.sh
dirname "$(print -P %x)"  # $(...) runs a command in a new process
dirname "${(%):-%x}"

% source apath/test.sh
apath
apath

显然,黑客的方式既更有效又更简短。

$_ 值得提到为 $0 的替代品。 如果您正在运行来自 Bash 的脚本,可将接受的答案缩短到:

DIR="$( dirname "$_" )"

请注意,这应该是您的脚本中的第一个声明。

请尝试以下交互式解决方案:

CWD="$(cd -P -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd -P)"

如 realpath 或 readlink 等命令可能无法使用(取决于操作系统)。

注意: 在 Bash 中,建议使用 ${BASH_SOURCE[0]} 而不是 $0,否则路径在提取文件时可能会破裂(源/)。

否则,您可以在Bash中尝试下列功能:

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

这个函数需要一个论点. 如果论点已经有绝对的路径,打印它如有,否则打印 $PWD 变量 + 文件名论点(没有./ 预定)。

相关:

如何将当前的工作目录设置为Bash中的脚本目录?Bash脚本绝对路径与OS X可靠路径为Bash脚本获得完整路径