How to copy complete content on terminal to a text file using commands ?(Not for one output but everything on terminal)

Question

How to copy complete content on terminal to a text file using commands .

Answer 1

You can use script. It will basically save everything printed on the terminal in that script session.

From man script:

script makes a typescript of everything printed on your terminal. 
It is useful for students who need a hardcopy record of an 
interactive session as proof of an assignment, as the typescript file 
can be printed out later with lpr(1).
You can start a script session by just typing script in the terminal, all the subsequent commands and their outputs will all be saved in a file named typescript in the current directory. You can save the result to a different file too by just starting script like:

script output.txt To logout of the script session (stop saving the contents), just type exit.

Here is an example:

$ script output.txt
Script started, file is output.txt
$ ls
output.txt  testfile.txt  foo.txt
$ exit
exit
Script done, file is output.txt

Now if I read the file:

$ cat output.txt
Script started on 2020-07-23 09:57:16+05:30
$ ls
output.txt  testfile.txt  foo.txt
$ exit
exit
Script done on 2020-07-23 09:57:34+05:30 

Answer 2

You can use screendump.

As in the man page:

 screendump - dump the contents of a virtual console to stdout

You'll need root privileges to run screendump, so use sudo.

Answer 3

As far as terminal emulators go ( GUI ) you can select the text with mouse and switch to text editor ( be it gedit or anything else ) and press Ctrl + Button 2 ( Scroll wheel on mouse and Right+Left click on touchpad )

With TTY you could use cat /dev/vcs1 to dump contents of TTY1.

Best approaches , however, should use terminal multiplexers such as screen , tmux, byobu or use script command to record the whole session to file.