循环遍历文件路径以检查目录是否存在

约翰尼·林

我想创建一个Linux bash脚本来循环目录路径，以检查每个目录是否确实存在。这只是一个简单的例子，

DIR="/etc/example/httpd/"
if [ -d "$DIR" ]; then
  echo "$dir exists"
else
  echo "$dir does not exists"
fi

我想回显该目录的输出

/etc exists
/etc/example does not exists
/etc/example/httpd does not exists

这是否意味着我必须执行很多cd命令才能做到这一点？

莉亚·格雷（Lea Gray）

你快到了。

这个想法是通过在/定界符上分割目录路径元素来迭代它们。

#!/usr/bin/env bash

DIR="/etc/example/httpd"

dir=
# While there is a path element delimited by / to read
# or the element is not empty (but not followed by a trailing /)
while read -r -d/ e || [ -n "$e" ]; do
  # If the element is not empty
  if [ -n "$e" ]; then
    # Postfix the element to the dir path with /
    dir+="/$e"
    if [ -d "$dir" ]; then
      echo "$dir exists"
    else
      echo "$dir does not exists"
    fi
  fi
done <<<"$DIR"

替代方法：

#!/usr/bin/env bash

DIR="/etc/example/httpd/"

# Set the Internal Field Separator to /
IFS=/
# Map the DIR path elements into an array arr
read -r -a arr <<<"$DIR"

# Starting at element 1 (skip element 0) and up to number of entries
for ((i=1; i<${#arr[@]}; i++)); do
  # Combine dir path from element 1 to element i of the array
  dir="/${arr[*]:1:i}"
  if [ -d "$dir" ]; then
    echo "$dir exists"
  else
    echo "$dir does not exists"
  fi
done

最后是POSIX Shell语法方法：

#!/usr/bin/env sh

DIR="/etc/example/httpd/"

dir=
IFS=/
# Iterate DIR path elmeents delimited by IFS /
for e in $DIR; do
  # If path element is not empty
  if [ -n "$e" ]; then
    # Append the element to the dir path with /
    dir="$dir/$e"
    if [ -d "$dir" ]; then
      echo "$dir exists"
    else
      echo "$dir does not exists"
    fi
  fi
done
exit

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