CMD: Export all the screen content to a text file
If you want to append a file instead of constantly making a new one/deleting the old one's content, use double > marks. A single > mark will overwrite all the file's content.
Overwrite file
MyCommand.exe>file.txt
^This will open file.txt if it already exists and overwrite the data, or create a new file and fill it with your output
Append file from its end-point
MyCommand.exe>>file.txt
^This will append file.txt from its current end of file if it already exists, or create a new file and fill it with your output.
Update #1 (advanced):
My batch-fu has improved over time, so here's some minor updates.
If you want to differentiate between error output and normal output for a program that correctly uses Standard streams, STDOUT/STDERR, you can do this with minor changes to the syntax. I'll just use > for overwriting for these examples, but they work perfectly fine with >> for append, in regards to file-piping output re-direction.
The 1 before the >> or > is the flag for STDOUT. If you need to actually output the number one or two before the re-direction symbols, this can lead to strange, unintuitive errors if you don't know about this mechanism. That's especially relevant when outputting a single result number into a file. 2 before the re-direction symbols is for STDERR.
Now that you know that you have more than one stream available, this is a good time to show the benefits of outputting to nul. Now, outputting to nul works the same way conceptually as outputting to a file. You don't see the content in your console. Instead of it going to file or your console output, it goes into the void.
STDERR to file and suppress STDOUT
MyCommand.exe 1>nul 2>errors.txt
STDERR to file to only log errors. Will keep STDOUT in console
MyCommand.exe 2>errors.txt
STDOUT to file and suppress STDERR
MyCommand.exe 1>file.txt 2>nul
STDOUT only to file. Will keep STDERR in console
MyCommand.exe 1>file.txt
STDOUT to one file and STDERR to another file
MyCommand.exe 1>stdout.txt 2>errors.txt
The only caveat I have here is that it can create a 0-byte file for an unused stream if one of the streams never gets used. Basically, if no errors occurred, you might end up with a 0-byte errors.txt file.
Update #2
I started noticing weird behavior when writing console apps that wrote directly to STDERR, and realized that if I wanted my error output to go to the same file when using basic piping, I either had to combine streams 1 and 2 or just use STDOUT. The problem with that problem is I didn't know about the correct way to combine streams, which is this:
%command% > outputfile 2>&1
Therefore, if you want all STDOUT and STDERR piped into the same stream, make sure to use that like so:
MyCommand.exe > file.txt 2>&1
The redirector actually defaults to 1> or 1>>, even if you don't explicitly use 1 in front of it if you don't use a number in front of it, and the 2>&1 combines the streams.
Update #3 (simple)
Null for Everything
If you want to completely suppress STDOUT and STDERR you can do it this way. As a warning not all text pipes use STDOUT and STDERR but it will work for a vast majority of use cases.
STD* to null
MyCommand.exe>nul 2>&1
Copying a CMD or Powershell session's command output
If all you want is the command output from a CMD or Powershell session that you just finished up, or any other shell for that matter you can usually just select that console from that session, CTRL + A to select all content, then CTRL + C to copy the content. Then you can do whatever you like with the copied content while it's in your clipboard.
Just see this page
in cmd type:
Command | clip
Then open a *.Txt file and Paste. That's it. Done.