Very long files are often hard to manipulate with a text editor. Suppose If you need to do it in a regular basis, then here is most simply, fast and handy command line solution!!!
Examples.
To print columns eg 1 and 3 from a file file1 into file2, we can use awk:
awk '{print $1, $3}' file1 > file2
To output only characters from column 8 to column 15 of file1, we can use cut:
cut -c 8-15 file1 > file2
To replace the word word1 with the word word2 in the file file1, we can use the sed command:
sed "s/word1/word2/g" file1 > file2
This is often a quicker way to get results than even opening a text editor.