屏幕截图 -l :非法选项

Question

我在SO上的许多页面中看到（例如这里：https://apple.stackexchange.com/questions/56561/how-do-i-find-the-windowid-to-pass-to-screencapture-l），你必须使用以下命令： screencapture -l为了捕获给定其 ID 的单个窗口。

但是，当我尝试在终端中输入screencapture -l时，出现此错误：

屏幕截图：非法选项 -- L

我已经检查了一个引用，实际上我看不到 -l 作为屏幕截图的可能属性：http://guides.macrumors.com/screencapture

你怎么解释这一点？我该如何解决这个问题？

Answer 1

不确定这是一个编程问题还是更适合 apple.stackexchange.com 的问题，但无论如何：

当我运行" screencapture -l "时，我看到这个：

screencapture: illegal option -- l
usage: screencapture [-icMPmwsWxSCUtoa] [files]
  -c         force screen capture to go to the clipboard
  -C         capture the cursor as well as the screen. only in non-interactive modes
  -d         display errors to the user graphically
  -i         capture screen interactively, by selection or window
               control key - causes screen shot to go to clipboard
               space key   - toggle between mouse selection and
                             window selection modes
               escape key  - cancels interactive screen shot
  -m         only capture the main monitor, undefined if -i is set
  -M         screen capture output will go to a new Mail message
  -o         in window capture mode, do not capture the shadow of the window
  -P         screen capture output will open in Preview
  -s         only allow mouse selection mode
  -S         in window capture mode, capture the screen not the window
  -t<format> image format to create, default is png (other options include pdf, jpg, tiff and other formats)
  -T<seconds> Take the picture after a delay of <seconds>, default is 5
  -w         only allow window selection mode
  -W         start interaction in window selection mode
  -x         do not play sounds
  -a         do not include windows attached to selected windows
  -r         do not add dpi meta data to image
  -l<windowid> capture this windowsid
  -R<x,y,w,h> capture screen rect
  files   where to save the screen capture, 1 file per screen

他们在上面的输出中没有说清楚（"windowsid"？），但看起来"-l"选项需要一个窗口ID，以便屏幕捕获将捕获屏幕上的单个窗口。