中国DOS联盟

cls

set todayFolder=%date:~0,4%%date:~5,2%%date:~8,2%

md %todayFolder%
cd %todayFolder%

md c
md d
md e

cd ..


ghost -clone,mode=pdump,src=1:1,dst=g:\ghost\%todayFolder%\d\c.gho -fx -z2 -sure
ghost -clone,mode=pdump,src=1:2,dst=g:\ghost\%todayFolder%\d\d.gho -fx -z2 -sure
ghost -clone,mode=pdump,src=1:3,dst=g:\ghost\%todayFolder%\e\e.gho -rb -z2 -sure

Under Windows, changing ghost to ghost32 can execute,
But when executing under Dos, the created directories c, d, e are in g:\ghost\ instead of g:\ghost\%todayFolder\.
Finally, c.gho, d.gho, e.gho are under g:\ghost\ instead of the g:\ghos\%todayFolder%\c\,
g:\ghost\%todayFolder%\d\, g:\ghost\%todayFolder%\e\ that I wanted.

I found that the path prompt when ghost is g:\ghost\\d\c.gho.
Is the %todayFolder% parameter invalid? How can it be done?

Try like this:

cls

set todayFolder=%date:~0,4%%date:~5,2%%date:~8,2%

md g:\ghost\%todayFolder%\c
md g:\ghost\%todayFolder%\d
md g:\ghost\%todayFolder%\e

ghost -clone,mode=pdump,src=1:1,dst=g:\ghost\%todayFolder%\c\c.gho -fx -z2 -sure
ghost -clone,mode=pdump,src=1:2,dst=g:\ghost\%todayFolder%\d\d.gho -fx -z2 -sure
ghost -clone,mode=pdump,src=1:3,dst=g:\ghost\%todayFolder%\e\e.gho -rb -z2 -sure

Thanks for your attention.

But the %todayFolder% parameter is still an empty string under DOS.
The created directory is in g:\ghost\\c.

It doesn't work... So annoying.

In a pure DOS environment, such a way of setting variables is not supported at all:
set todayFolder=%date:~0,4%%date:~5,2%%date:~8,2%

This setting method can only be used in the NT cmd environment.

Re chjlcn:

　　In a pure DOS environment, there is another method to obtain date variables, which can be found in the code on the 7th floor of {8905} An Oddity in Batch Programming.

　　In addition, if it is to be used as a file or directory name in a system that does not support long filenames (the MSDOS7.10 on this site supports it), you need to pay attention to the number of digits of "year" in the date variable; if it is a 4-digit year, the last two characters of the date variable will be truncated. It may be "05" of 2005, or "06" of 08-06, depending on the system's date format.

### 首先分析 `echo exit | %comspec% /k prompt set %1=%2$_:: > _GetVar.bat` 这一整句的含义：

- `echo exit`：`echo` 命令用于输出文本，这里输出 `exit` 这个字符串。
- `|`：管道符号，将前面 `echo exit` 的输出作为后面命令的输入。
- `%comspec%`：获取系统的命令行解释器路径，通常是 `cmd.exe`（在 Windows 系统中）。
- `/k`：`%comspec%` 的参数，表示执行完命令后不关闭命令提示符窗口。
- `prompt set %1=%2`：`prompt` 命令在这里被用来设置一个临时的命令，这里的 `%1` 和 `%2` 是脚本的参数，假设脚本调用时传入了两个参数，`%1` 会被替换为第一个参数，`%2` 会被替换为第二个参数，比如如果传入的是 `varName` 和 `varValue`，那么这里就会变成 `prompt set varName=varValue`。
- `$_`：这里 `$_` 应该是用来表示一个换行符，在批处理中可以用 `$_` 来插入一个换行。
- `::`：在批处理中，`::` 后面的内容被视为注释，这里主要是为了让后面的 `>` 重定向到文件时的语法正确。
- `> _GetVar.bat`：将前面通过管道传递过来的内容重定向到名为 `_GetVar.bat` 的文件中。

整体来说，这一句的作用是：通过 `echo` 输出 `exit`，然后利用管道将其作为输入传递给 `%comspec% /k prompt set %1=%2$_::` 命令，最后将这个组合的结果重定向到 `_GetVar.bat` 文件中，从而在这个临时批处理文件中设置了一个基于传入参数的 `prompt` 相关命令。

Hehe, the key is this sentence! Understand it slowly by yourself. This is the essence in the skills of batch processing.

@climbing

Can you give some hints on which commands to learn?
Are there any relevant e-books for download?

Re chjlcn:

　　To be really detailed, it might be quite complicated because of my limited expression ability. I often can't grasp what the readers already know and what they don't. Maybe in future DOS books, I will write a special article to explain the techniques of this code.

　　Currently, I can only simply provide some ideas to master it:

　　1. Comment out the for statement that deletes _GetVar.bat, then execute getvar today=$D in the command line to view the content of _GetVar.bat;

　　2. Remove the redirection part > _GetVar.bat of the echo line, then execute getvar today=$D in the command line to view the output content on the screen;

　　3. Execute separately in the command line:
　　　echo exit | %comspec% /k prompt set today=$D$_::
　　　%comspec% /k prompt set today=$D$_::
　　　prompt set today=$D$_::
　　Then observe their respective output contents, and I believe you will have some insights.

Last edited by willsort on 2005-8-8 at 13:26 ]

I found that %myDate:~0,2% is not supported under DOS. Are there any functions to get some characters from a string?

Has willsort already provided a solution? Haven't you studied it carefully?