文件类型测试

-e 条件运算符测试文件是否存在（包括所有文件类型：目录等）。

if [[ -e $filename ]]; then
  echo "$filename exists"
fi

还有针对特定文件类型的测试。

if [[ -f $filename ]]; then
  echo "$filename is a regular file"
elif [[ -d $filename ]]; then
  echo "$filename is a directory"
elif [[ -p $filename ]]; then
  echo "$filename is a named pipe"
elif [[ -S $filename ]]; then
  echo "$filename is a named socket"
elif [[ -b $filename ]]; then
  echo "$filename is a block device"
elif [[ -c $filename ]]; then
  echo "$filename is a character device"
fi
if [[ -L $filename ]]; then
  echo "$filename is a symbolic link (to any file type)"
fi

对于符号链接，除了 -L 之外，这些测试适用于目标，并且对于断开的链接返回 false。

if [[ -L $filename || -e $filename ]]; then
  echo "$filename exists (but may be a broken symbolic link)"
fi

if [[ -L $filename && ! -e $filename ]]; then
  echo "$filename is a broken symbolic link"
fi