CMD Command Prompt Boot Camp

A CMD/'DOS' Command Line Boot Camp

This section will be a mini boot-camp / accelerated crash course on using the CMD/DOS Command Prompt. It won't cover basic file system navigation, I assume you can complete the CLI Task Test, if not run through Zen's CLI Crash Course first. It won't be as long as the PowerShell Boot Camp, because beyond a few specific cases: you should just focus on learning PowerShell instead. Enough to quickly get up to speed at the CMD Prompt and know what to Google for if you get stuck. For the basics see the CMD/DOS Essentials page.

Using the CMD Command Prompt

Most commands use slash: / or dash: - to start options/switches, as in /ah or -a. Most commands support /? to get help, as in dir /?. When you don't know what options to use, try that first. For more info on CMD Help see the Essentials page.

The CMD/DOS Command Line supports the pipeline using the vertical pipe character: | but chaining together multiple commands always easy. Common ones are:

• more to show text one screen-full at a time
  robocopy /? | more will show the Help Text and pause after each page
  You can also use more to display a file a page at a time: more C:\Windows\debug\WIA\wiatrace.log
  Note: to display a file without pausing use type, as in: type C:\Windows\System32\WimBootCompress.ini
• find or findstr to filter and show only matching [or not matching] lines. findstr supports RegEx for more complex searching/filtering
  findstr /L /I "Successfully "c:\logfiles\*.txt" to search a bunch of .TXT files for the word "Successfully".
• sort to sort the lines of the output, for example:
  type randomLines.txt | sort > sortedLines.txt and capture the output with redirection.
• clip to copy the text output to the Windows Clipboard:
  type c:\temp\logfile.txt | clip and the contents of the file would be in the Clipboard
• The pipeline can continue from command to command, but with CMD it gets more complicated as it's all raw text:
  A made-up example might look like: someCommand.exe list -option %windir% /switch --etc | find /I "value" | sort | more

To do more complex filtering and passing of output to another command's input you probably need cut, tail, tr, sed, uniq, etc: UNIX/Linux commands that have been ported to Windows. You can find some at GNUWin32 (they are not built in to Windows). But unless you're familiar with Linux CLI already, it's easier to to learn PowerShell. In CMD/DOS everything is plain-text, which may initially make things seem easier but eventually it's harder and less accommodating of changes. PowerShell is all Objects.

Command redirection using the greater than symbol > can be helpful, if you add > to create a file, or >> to append to a file, you can capture the output of any command. Such as: dir c:\windows > c:\winfiles.txt and then perhaps edit the file in Notepad (eg. to remove some header lines) before further processing it.

More advanced CMD Usage

If you're not sure what the command you're looking for is, you can list the basic built-in CMD commands with help, and you can search for external (included or downloaded) .EXE file with where.exe, including using wildcards. So you can search for any .EXE that includes "exec" with where.exe *exec*.exe - which might show the MSIEXEC and PSEXEC.EXE (if you had it installed). So searching for where.exe *dfs*.exe would show any DFS related commands.
Note: Where (without .exe) is also a built-in PowerShell command, so using .exe with where.exe will let you use it in PowerShell too.

CMD has environment variables which you can see with the SET command, and reference them with percent signs % on either side, such as %windir% or %USERNAME% to reference the Windows directory (ie. c:\windows) or the current logged on username in commands and scripts.

You can use set to not just display but also add or change an environment variable (within the lifetime the Console window stays open, such as set location=c:\temp\folder and then reference %location% later on such as copy *.* %location% would resolve to copy *.* c:\temp\folder. Using environment variables can make commands and scripts more flexible by either using system defined values (which can change) or only having to update a variable in one place.

You can make a Batch Script by pasting all the lines you want to run into a plain text file and saving it as a .BAT file, then running it is like typing those commands at the prompt, one line at a time - making it easy to carry out the same set of commands over and over, or on different systems.

If you need to run a .BAT script or a CMD built-in command (such as dir or copy) from some "run a command" process you can do so using cmd /c script.bat or cmd /c dir and CMD.exe will run the script/command and then exit.

CMD also support conditional branching (IF) and looping (FOR, GOTO or CALL) but it really isn't worth learning to write complex scripts for CMD processing - too much arcane legacy baggage and strange syntax. If you need to write something more complex: Use PowerShell - it's included in all supported Windows OS, can be installed on older OS, and is much more flexible, regular, and friendly.