问题
What does /p stand for in set /p=? I know that / enables a switch, and I'm fairly sure that I know /a is for arithmetic. I've heard numerous rumours, some saying /p is for prompt, others stating it stands for print. The only reason I slightly doubt it is prompt is because in many cases it does not ask for a prompt, yet prints on the screen, such as
<nul set /p=This will not generate a new line
But what I want to know is: Do we really know what it stands for?
Bonus points for anyone who knows what all the switches for ping stand for, such as -n, -w, -a, -s, and what the switch /L in for is meant to stand for. (L = number?)
Even More Bonus Points for anyone who can name any other seemingly stupid switches in batch file
Please understand that I already know what all these switches and prefixes and whatnot mean, I am not asking for their meaning nor purpose. Thanks in advance.
回答1:
For future reference, you can get help for any command by using the /? switch, which should explain what switches do what.
According to the set /? screen, the format for set /p is SET /P variable=[promptString] which would indicate that the p in /p is "prompt." It just prints in your example because <nul passes in a nul character which immediately ends the prompt so it just acts like it's printing. It's still technically prompting for input, it's just immediately receiving it.
/L in for /L generates a List of numbers.
From ping /?:
Usage: ping [-t] [-a] [-n count] [-l size] [-f] [-i TTL] [-v TOS]
[-r count] [-s count] [[-j host-list] | [-k host-list]]
[-w timeout] [-R] [-S srcaddr] [-4] [-6] target_name
Options:
-t Ping the specified host until stopped.
To see statistics and continue - type Control-Break;
To stop - type Control-C.
-a Resolve addresses to hostnames.
-n count Number of echo requests to send.
-l size Send buffer size.
-f Set Don't Fragment flag in packet (IPv4-only).
-i TTL Time To Live.
-v TOS Type Of Service (IPv4-only. This setting has been deprecated
and has no effect on the type of service field in the IP Header).
-r count Record route for count hops (IPv4-only).
-s count Timestamp for count hops (IPv4-only).
-j host-list Loose source route along host-list (IPv4-only).
-k host-list Strict source route along host-list (IPv4-only).
-w timeout Timeout in milliseconds to wait for each reply.
-R Use routing header to test reverse route also (IPv6-only).
-S srcaddr Source address to use.
-4 Force using IPv4.
-6 Force using IPv6.
回答2:
The /P switch allows you to set the value of a variable to a line of input entered by the user. Displays the specified promptString before reading the line of input. The promptString can be empty.
Two ways I've used it... first:
SET /P variable=
When batch file reaches this point (when left blank) it will halt and wait for user input. Input then becomes variable.
And second:
SET /P variable=<%temp%\filename.txt
Will set variable to contents (the first line) of the txt file. This method won't work unless the /P is included. Both tested on Windows 8.1 Pro, but it's the same on 7 and 10.
来源：https://stackoverflow.com/questions/27773805/what-does-p-mean-in-set-p