加班中，在调研函数计算，使用nodejs做一个demo的时候，在比较深的路径下下载了一张图片。
不想用finder逐层文件夹寻找，而是希望直接打开，顺手敲了一下open 1.png命令，果然打开了。
which open看一下位置，果然是mac系统自带，位于/usr/bin/open。
open -h查看提示：
demo $ open -h
Warning: Xcode platforms folder not found at "/Library/Developer/CommandLineTools". You may have invalid DEVELOPER_DIR or stale xcode-select setting.
Usage: open [-e] [-t] [-f] [-W] [-R] [-n] [-g] [-h] [-s <partial SDK name>][-b <bundle identifier>] [-a <application>] [filenames] [--args arguments]
Help: Open opens files from a shell.
By default, opens each file using the default application for that file.
If the file is in the form of a URL, the file will be opened as a URL.
Options:
-a Opens with the specified application.
-b Opens with the specified application bundle identifier.
-e Opens with TextEdit.
-t Opens with default text editor.
-f Reads input from standard input and opens with TextEdit.
-F --fresh Launches the app fresh, that is, without restoring windows. Saved persistent state is lost, excluding Untitled documents.
-R, --reveal Selects in the Finder instead of opening.
-W, --wait-apps Blocks until the used applications are closed (even if they were already running).
--args All remaining arguments are passed in argv to the application's main() function instead of opened.
-n, --new Open a new instance of the application even if one is already running.
-j, --hide Launches the app hidden.
-g, --background Does not bring the application to the foreground.
-h, --header Searches header file locations for headers matching the given filenames, and opens them.
-s For -h, the SDK to use; if supplied, only SDKs whose names contain the argument value are searched.
Otherwise the highest versioned SDK in each platform is used.根据提示内容，可知open就是从命令行执行打开。包括本地文件和远程文件（浏览器打开）。
关于使用参数和一些常用的应用、网站等打开方式：
1、 open -a
open -a qq
2、打开网页
open https://www.zhihu.com/
3、open -f
从标准输入中读取输入内容，并通过文本编辑器打开。
示例： ls |open -f
