#!/usr/bin/env bash

SCRIPT_DIR="$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"

是一个有用的单行代码，无论从何处调用脚本，它都会为您提供脚本的完整目录名称.

is a useful one-liner which will give you the full directory name of the script no matter where it is being called from.

只要用于查找脚本的路径的最后一个组件不是符号链接(目录链接就可以)，它就会起作用.如果您还想解析脚本本身的任何链接，则需要多行解决方案:

It will work as long as the last component of the path used to find the script is not a symlink (directory links are OK). If you also want to resolve any links to the script itself, you need a multi-line solution:

#!/usr/bin/env bash

SOURCE="${BASH_SOURCE[0]}"
while [ -h "$SOURCE" ]; do # resolve $SOURCE until the file is no longer a symlink
  DIR="$( cd -P "$( dirname "$SOURCE" )" >/dev/null 2>&1 && pwd )"
  SOURCE="$(readlink "$SOURCE")"
  [[ $SOURCE != /* ]] && SOURCE="$DIR/$SOURCE" # if $SOURCE was a relative symlink, we need to resolve it relative to the path where the symlink file was located
done
DIR="$( cd -P "$( dirname "$SOURCE" )" >/dev/null 2>&1 && pwd )"

最后一个将适用于别名、source、bash -c、符号链接等的任意组合.

This last one will work with any combination of aliases, source, bash -c, symlinks, etc.

注意:如果在运行此代码段之前cd到不同的目录，结果可能不正确！

Beware: if you cd to a different directory before running this snippet, the result may be incorrect!

另外，注意$CDPATH 问题 和 stderr 输出副作用，如果用户巧妙地覆盖了 cd 以将输出重定向到 stderr(包括转义序列，例如调用 update_terminal_cwd >&2 在 Mac 上).在 >/dev/null 2>&1 命令的末尾添加 >/dev/null 2&1 将处理这两种可能性.

Also, watch out for $CDPATH gotchas, and stderr output side effects if the user has smartly overridden cd to redirect output to stderr instead (including escape sequences, such as when calling update_terminal_cwd >&2 on Mac). Adding >/dev/null 2>&1 at the end of your cd command will take care of both possibilities.

要了解它是如何工作的，请尝试运行这个更详细的表单:

To understand how it works, try running this more verbose form:

#!/usr/bin/env bash

SOURCE="${BASH_SOURCE[0]}"
while [ -h "$SOURCE" ]; do # resolve $SOURCE until the file is no longer a symlink
  TARGET="$(readlink "$SOURCE")"
  if [[ $TARGET == /* ]]; then
    echo "SOURCE '$SOURCE' is an absolute symlink to '$TARGET'"
    SOURCE="$TARGET"
  else
    DIR="$( dirname "$SOURCE" )"
    echo "SOURCE '$SOURCE' is a relative symlink to '$TARGET' (relative to '$DIR')"
    SOURCE="$DIR/$TARGET" # if $SOURCE was a relative symlink, we need to resolve it relative to the path where the symlink file was located
  fi
done
echo "SOURCE is '$SOURCE'"
RDIR="$( dirname "$SOURCE" )"
DIR="$( cd -P "$( dirname "$SOURCE" )" >/dev/null 2>&1 && pwd )"
if [ "$DIR" != "$RDIR" ]; then
  echo "DIR '$RDIR' resolves to '$DIR'"
fi
echo "DIR is '$DIR'"

它会打印如下内容:

SOURCE './scriptdir.sh' is a relative symlink to 'sym2/scriptdir.sh' (relative to '.')
SOURCE is './sym2/scriptdir.sh'
DIR './sym2' resolves to '/home/ubuntu/dotfiles/fo fo/real/real1/real2'
DIR is '/home/ubuntu/dotfiles/fo fo/real/real1/real2'