UNIX for Advanced & Expert Users

A friend routed some console output to a file for me. The problem is he used backspace and escape sequences all over the place. Using vi to view the file makes it difficult to read. Is there a program that will process the backspaces and remove the escape sequences?

e.g.,

Code:

bash-3.00$ pwd^[[K^H^H^Hcd ~
would be cleaned to be
bash-3.00$ cd ~

What are these characters - really control chars and escape sequences or just ASCII representation of them?

They are real.

---------- Post updated at 04:39 PM ---------- Previous update was at 12:40 PM ----------

The reason you see the ascii representation in my example is because that is what vi displays when it reads the control characters.

These are various control characters depending upon, tab, space, CTRL C, ESC, CTRL Z, backspace and others depending upon shell you are using.

As per my experience, there isn't any program which will do it for you. You can't even do something like "Search and Replace" as we do with newline characters in vi, because of key sequences pressed.
You need to use your experience for that to analyze.

Similar type of problem exists when you use putty log feature with "All Session Output".

Sorry, but i think it is indeed possible. Here is a possible solution in sed for the backspace key - other key sequences can be done similarily. (I assume "^H" [ONE character!] to be the backspace sequence here.)

Code:

:loop
/.^H/ {
       s/.^H//
       b loop
     }

save this to a file and issue:

Code:

sed -f /path/to/cmdfile /path/to/infile > /path/to/outfile

This sed-script looks for a line with a character followed by a backspace, removes both and loops until no backspace character can be found any more. This way sequences of backspaces are deleted along with the characters they were used to remove. For example:

Code:

abcd^H^He    <- input
abc^He       <- after one pass of the loop
abe          <- after second pass of the loop

I hope this helps.

bakunin

Thanks for correcting me.
But I will check by myself, and let you know.