How to add 100 spaces at end of each line of a file in Unix

Question

I have a file which is supposed to contain 200 characters in each line. I received a source file with only 100 characters in each line. I need to add 100 extra white spaces to each line now. If it were few blank spaces, we could have used sed like:

 sed 's/$/     /' filename > newfilename

Since it's 100 spaces, can anyone tell me is it possible to add in Unix?

Answer 1

If you want to have fixed n chars per line (don't trust the input file has exact m chars per line) follow this. For the input file with varying number of chars per line:

$ cat file
1
12
123
1234
12345

extend to 10 chars per line.

$ awk '{printf "%-10s\n", $0}' file | cat -e

1         $
12        $
123       $
1234      $
12345     $

Obviously change 10 to 200 in your script. Here $ shows end of line, it's not there as a character. You don't need cat -e, here just to show the line is extended.

Answer 2

If you use Bash, you can still use sed, but use some readline functionality to keep you from manually typing 100 spaces (see manual for "Readline arguments").

You start typing normally:

sed 's/$/

Now, you want to insert 100 spaces. You can do this by prepending hitting the space bar with a readline argument to indicate that you want it to happen 100 times, i.e., you manually enter what would look like this as a readline keybinding:

M-1 0 0 \040

Or, if your meta key is the alt key: Alt+1 00Space

This inserts 100 spaces, and you get

sed 's/$/                                                                                                    /' filename

after typing the rest of the command.

This is useful for working in an interactive shell, but not very pretty for scripts – use any of the other solutions for that.