官方原文链接: https://help.dropbox.com/zh-cn/files-folders/restore-delete/ignored-files
windows:
Set-Content -Path 'C:\Users\yourname\Dropbox(Personal)\YourFileName.pdf' -Stream com.dropbox.ignored -Value 1
Mac
xattr -w com.dropbox.ignored 1 /Users/yourname/Dropbox\ \(Personal\)/YourFileName.pdf
Linux
attr -s com.dropbox.ignored -V 1 /Users/yourname/Dropbox\ \(Personal\)/YourFileName.pdf