“Cmd.exe”的意思、由来-开放百科全书

词条

Cmd.exe

释义

Operation
Comparison with MS-DOS Prompt
See also
References
Further reading

{{distinguish|COMMAND.COM}}{{Redirect|Command Prompt|the concept|command prompt}}{{Lowercase title}}{{Refimprove|date=July 2007}}{{Infobox software
| name = Command Prompt (cmd.exe)
| logo = Command prompt icon (windows).png
| logo_size = 48px
| screenshot = Command Prompt on Windows 10 RTM.png
| screenshot_size = 300px
| caption = Command Prompt in Windows 10
| developer = Microsoft, IBM, ReactOS Contributors
| other_names = Windows Command Processor
| replaces = COMMAND.COM
| operating system = Microsoft Windows, OS/2, ReactOS
| genre = Command-line interpreter
}}Command Prompt, also known as cmd.exe or cmd (after its executable file name), is the command-line interpreter on Windows NT, Windows CE, OS/2, eComStation and ReactOS operating systems. It is the counterpart of COMMAND.COM in DOS and Windows 9x systems (where it is also called "MS-DOS Prompt"), and analogous to the Unix shells used on Unix-like systems. The initial version of Command Prompt for Windows NT was developed by Therese Stowell.^[1]

Operation

Command Prompt interacts with the user through a command-line interface. In Windows, this interface is implemented through Win32 console. Command Prompt may take advantage of features available to native programs of its own platform. For example, in OS/2, it can use real pipes in command pipelines, allowing both sides of the pipeline to run concurrently. As a result, it is possible to redirect the standard error stream. (COMMAND.COM uses temporary files, and runs the two sides serially, one after the other.)

Comparison with MS-DOS Prompt

In Windows, Command Prompt is compatible with COMMAND.COM but provides the following extensions over it:

Provides more detailed error messages than the blanket "Bad command or file name" (in the case of malformed commands) of COMMAND.COM. In the OS/2, errors are reported in the chosen language of the system, their text being taken from the system message files. The HELP command can then be issued with the error message number to obtain further information.
Supports using of arrow keys to scroll through command history. This function was only available to COMMAND.COM via an external component called {{mono|DOSKEY}}.
Adds command-line completion for file and folder paths.
Treats the caret character ({{mono|^}}) as the escape character; in other words, the character following it is to be taken literally. There are special characters in Command Prompt and COMMAND.COM (e.g. "{{mono|<}}", "{{mono|>}}" and "|") that are meant to alter the behavior of the command line processor. The caret character forces the command line processor to interpret them literally.
Supports delayed variable expansion{{Elucidate|date=January 2015}} (Windows 2000 and later), fixing DOS idioms that made using control structures hard and complex.^[2] The extensions can be disabled, providing a stricter compatibility mode.

Internal commands have also been improved:

The {{mono|DelTree}} command was merged into the {{mono|RD}} command, as part of its {{mono|/S}} switch.
{{mono|SetLocal}} and {{mono|EndLocal}} commands limit the scope of changes to the environment. Changes made to the command line environment after {{mono|SetLocal}} commands are local to the batch file. {{mono|EndLocal}} command restores the previous settings.^[3]
The {{mono|Call}} command allows subroutines within batch file. The {{mono|Call}} command in COMMAND.COM only supports calling external batch files.
File name parser extensions to the {{mono|Set}} command are comparable with C shell.{{Elucidate|reason = |date=October 2015}}
The {{mono|Set}} command can perform expression evaluation.
An expansion of the {{mono|For}} command supports parsing files and arbitrary sets in addition to file names.
The new {{mono|PushD}} and {{mono|PopD}} commands provide access past navigated paths similar to "forward" and "back" buttons in a web browser or File Explorer.
The conditional {{mono|IF}} command can perform case-insensitive comparisons and numeric equality and inequality comparisons in addition to case-sensitive string comparisons. This was available in DR-DOS (by Novell) but not in PC DOS (by IBM) or MS-DOS (by Microsoft).

References

1. ^{{Cite book |title=Showstopper! The Breakneck Race to Create Windows NT and the Next Generation at Microsoft |first=G. Pascal |last=Zachary | year=1994 |publisher=The Free Press |isbn=0-02-935671-7}}
2. ^{{Cite web |title=Windows 2000 delayed environment variable expansion |url=http://windowsitpro.com/windows/jsi-tip-3240-windows-2000-delayed-environment-variable-expansion|work=Windows IT Pro|accessdate=13 July 2015}}
3. ^{{Cite web|title=Setlocal|url=https://technet.microsoft.com/en-us/library/bb491001.aspx|work=TechNet|publisher=Microsoft|accessdate=13 January 2015}}

Operation

Comparison with MS-DOS Prompt

See also

References

Further reading