CMD/DOS Essentials

CMD/DOS - The Essentials

Commands and Options
Getting Help
Also Worth Knowing

First: The "Command Prompt", as it is officially known in Windows, is the legacy CLI (though it isn't going anywhere) provided by CMD.EXE which resembles the MS-DOS Prompt (provided by COMMAND.COM). CMD.EXE provides some built-in commands, and others are external .EXE commands - but we'll consider anything provided my Microsoft in MS Windows to be "built-in".

The CMD Command Prompt aka DOS Prompt carries a lot of legacy baggage, in fact most of the commands are made to operate identically to how they worked in MS-DOS, but with some enhancements. This is both a blessing and a curse.

There's less uniform standardization and consistency with "DOS" commands (even ones provided by Microsoft with Windows, due to legacy reasons) but even less so with random Console .EXE files you may download and run. (though many are trying to follow modern Linux/Bash/macOS standards)

Generally I would recommend using PowerShell instead, but some commands may work better in the CMD Command Prompt, especially if they have switches requiring "quoted" values.

To start the Command Prompt run cmd.exe, or look for "Command Prompt" in your Start menu.

Type commands at the C:\> prompt and press Enter after each.

In the example above the command cd "some folder" was typed at the C:\> prompt, the prompt changed to show the working directory was changed to the "some folder" directory, a valid command was typed, the results came back (showing where the cmd.exe file is located), and then an unknown command was tried - resulting in the error message which says exactly that - the command wasn't recognized. Now the C:\some folder> prompt waits for the next command.

Commands and Options

Included Windows console commands (both CMD built-in commands and external .EXE commands) are often short (dir instead of "list directory" or md instead of "make directory") and sometimes cryptic (such as qwinsta instead of "query windows station"); often because these commands have been around since the days of MS-DOS and 8 character filename limits. Generally there is no regular pattern all command names follow.

Whereas PowerShell has cmdlets following Verb-Noun format (Get-Content, Set-Content, etc) CMD/DOS commands usually wrap all verb/action functionality into the same command, either using switches/options (like command.exe /add or command.exe /remove) or subcommands (like command.exe list or command.exe edit -option).
PowerShell has aliases for many of these older DOS/CMD commands (such as dir, copy, md/mkdir, ren, del, etc) meaning if you learn these you'll be able to operate in both CLI Shells.
All Command Prompt commands will output plain-text: what you see is exactly what is output.
Third Party downloaded console commands may be equally short or cryptic, especially if they are ports of Linux/macOS/Bash utilities. You can also run Windows GUI commands which will just start the program as if you had double-clicked it (like regedit.exe) however some may also have useful switches/options.
You can run any .EXE so long as it is in the PATH environment variable.
If it's not, then you'll need to specify the whole path, such as: c:\windows\system32\inetsrv\appcmd.exe,
Or you'll need to change to the folder (cd c:\windows\system32\inetsrv) and then run appcmd.exe

Parameters/switches/options for CMD/DOS Commands are separated from commands with a Space and usually a single dash - or slash /, as in -AH or /B.

You need the space after the command and the dash or slash, you can't type dir-ah (that would be a separate command).
CMD/DOS Commands can each have their own standard for options/switches, usually each set of switches is separated by a space:

Sometimes you add values after the switch, like: /a value
Or you append it after a colon or equals, such as -a:value or -a=value
Sometimes you don't need any punctuation and you just add them together as in /ah or /ahs appending either H or HS to /A
(In this case the switch is still /A, the H or HS is just the value for /A)
Unix/Linux/Bash ported or inspired commands may use double dash -- for some longer options like --listall
And sometimes switches to be stacked/combined (where /a /o /n can be written as /aon or as /a/o/n without spaces)
Finally, some commands may not use a dash or slash and just have subcommands or options listed after the main command (such as git status not /status or -status)
Or mix and match, such as: git log --oneline -n 10
Note: git is the command for Git, the source code repository package. log is a sub-command for Git. --oneline is a parameter for the "Log" sub-command. And -n is another option for Log with 10 being the value passed to -n
For more info on using Git from the command line see my separate guide here.
Of course single letter switches can have different meanings to different commands...

The main point is: Every command can be different so check the help text!

Getting Help

Getting Help for CMD/DOS commands can also vary. A short list of the basic included Windows console commands can be found by running help but this by no means includes them all (mostly just the older legacy MS-DOS derived commands).

Usually you need to pass a switch or option for DOS/CMD/Console .EXE commands to show their Help text. It can vary, but one of these should work:

-h, /h, --help, /?, -?, or just ?
As in ping /?

If the Help Text is too long add | more after, as in: chkdsk /? | more. But don't just type the name of the command with no switches to see what it may do until you've tried /?, /h, etc. because some commands will do something even with no options/switches. For example: IISRESET will restart all IIS Web Services if you provide no options, which may not be what you want/expect! iisreset /? will show the help.

Sometimes you can just type the command with no options and it will provide help, but sometimes the command doesn't require options and it just runs!
If this happens and it appears to hang (likely waiting for input) try pressing any of: Ctrl+C, Ctrl+Z, or Ctrl+D to either cancel the command or end the input.

While the meaning of console CLI switches/options/arguments can vary usually how they are represented in Help Text is fairly standard.

In the example above, copy /? shows there is only one required parameter, the source as it is not enclosed in [square brackets]. The other switches and options (such as /D, /V, etc) are in [square brackets] so they are optional, as is the destination.
If options are separated by a vertical pipe | character that means you can use only one of those options (either /A or /B). Then there is usually a list of what each option/switch means.
Whether you can specify options in lower case or use - instead of / depends on the command, sometimes if there isn't a /B and a /b option you can use either, other times not, other times they could be different options entirely!

Also worth knowing

There's Tab completion only for files/directories at the CMD Command Prompt. Type a command and if you need to specify a file/folder start typing the name and press the Tab key to cycle through all matching files/folders. For example: type cd \win[press TAB] and it will complete to cd C:\Windows

Another trick you can sometimes use: the * wildcard. If it will match only one folder, as in cd \win*, it will resolve to the first folder starting with "win" in the root of the drive.

The Command Prompt is (generally) NOT Case Sensitive. You can type DIR, dir, DiR, etc.

Files are also NOT Case Sensitive, though they do retain case (so test.txt = TEST.TXT = Test.TxT, they all reference the same file). Note: UNIX/Linux/macOS IS Case Sensitive.

are

Because of the need to put "quotes" around files/folders with spaces in them you'll soon discover it's best to avoid spaces in names if possible (or use Tab Completion).

To run a script you can just run it as any other built-in or external .EXE command, so long as it is in the PATH it will be found.

CMD scripts are ASCII text files that have a .BAT or .CMD extension (not .BATCH or .COM). Windows and most Email/AV/Spam filters will consider them executable so will be blocked from attachments; generally if you want to email a .BAT/.CMD file rename it to something like filename_rename-me-BAT.txt (but don't use .bat.txt in case the double extension is caught as suspicious too).
The extension .BAT means "a file containing a batch of commands to run" and .CMD is for CMD, the command/shell processor.

You can enter any CMD/DOS command at the prompt and test/build scripts one command at a time - that is: variables and whatnot persist between commands (but not between sessions - if you close the window everything not saved to a file is gone). However the Shell itself only has limited expression evaluation abilities, you can can't just type 2 + 2 and get back 4 like you can with PowerShell.

CMD.EXE is a Windows program, so be mindful of Run as Administrator, Admin Rights, UAC, etc. If you can't do something, try running your Command Prompt as an Administrator.