Install Midnight commander (MC) in Linux,
or Total commander in Windows.
Go to the folder with the file you want to view.
Press F3 to view the file. This step is usually much faster than loading the file in Gedit (Linux) or Notepad (Windows)
Press F7 to search for the text of interest.
Hold SHIFT and select the text with mouse.
CTRL + INS to copy the text. Or right click and copy.
Simply select and CTRL + INS or CTRL + C for copying