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I'm using the linux 'script' command http://www.linuxcommand.org/man_pages/script1.html to track some interactive sessions. The output files from that contain unprintable characters, including my backspace keystrokes.

Is there a way to tidy these output files up so they only contain what was displayed on screen?

Or is there another way to record an interactive shell session (input and output)?

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9 Answers 9

up vote 10 down vote accepted

If you want to view the file, then you can send the output through col -bp; this interprets the control characters. Then you can pipe through less, if you like.

col -bp typescript | less -R

On some systems col wouldn't accept a filename argument, use this syntax instead:

col -bp <typescript | less -R
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on my system, col wouldn't accept a filename, so I did col -bp < typescript and got what I wanted. –  Andrew Mar 19 '12 at 12:19

If you want to write the output to a file:

col -bp < typescript >>newfile

use unix2dos command to convert file to Windows format if you want

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I used cat filename which removes control characters :-)

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imo this is a nicer answer, since it really removes all the control characters. –  Nathanael Farley Sep 23 '14 at 11:02
on OSX, cat does not remove colour control characters... –  Nick Dec 10 '14 at 18:04

For a large quantity of script output, I'd hack a perl script together iteratively. Otherwise hand edit with a good editor.

There is unlikely to be an existing automated method of removing control characters from script output in a way that reproduces what was displayed on the screen at certain important moments (such as when the host was waiting for that first character of some user input).

For example the screen might be blank except for Andrew $, if you then typed rm /* and pressed backspace twelve times (far more than needed), what gets shown on the screen at the end of that depends on what shell was running, what your current stty settings are (which you might change partway through a session) and probably some other factors too.

The above applies to any automated method of continuously capturing input and output. The main alternative is taking "screen shots" or cutting and pasting the screen at appropriate times during the session (which is what I do for user guides, notes for a day-log, etc).

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An answer to the second part of my question is to use the logging facility in gnu screen: ^A H from within a running screen session. The documentation is at http://www.gnu.org/software/screen/manual/screen.html#Logging

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I found the answer that dewtall provided to a similar question on the Unix board to be more effective at removing control characters from the output of script if you are in an environment where Perl is available to you.

dewtall's script:

while (<>) {
    s/ \e[ #%()*+\-.\/]. |
       \r | # Remove extra carriage returns also
       (?:\e\[|\x9b) [ -?]* [@-~] | # CSI ... Cmd
       (?:\e\]|\x9d) .*? (?:\e\\|[\a\x9c]) | # OSC ... (ST|BEL)
       (?:\e[P^_]|[\x90\x9e\x9f]) .*? (?:\e\\|\x9c) | # (DCS|PM|APC) ... ST
       \e.|[\x80-\x9f] //xg;
       1 while s/[^\b][\b]//g;  # remove all non-backspace followed by backspace

To remove the control characters:

./dewtalls-script.pl < output-from-script-that-needs-control-characters-removed
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cat typescript | perl -pe 's/\e([^\[\]]|\[.*?[a-zA-Z]|\].*?\a)//g' | col -b > typescript-processed
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If what you're after is to record your commands (e.g. to later turn them into a bash script), then a reasonable hack is to run script(1), then inside it run

bash -x

Afterwards grep the output file (usually "typescript") looking for lines starting with a "+". The regular expression ^\+ will do the trick.

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col -bp processes the backspaces as desired (AFAIK). But it mangles the color escape sequences. It might be good to remove the color sequences first, then process the backspaces, if possible.

This is a very common need, and I'm surprised there are not more solutions to it. It is extremely common to script a session, then somebody has a need to review the procedure. You want to cut out all the little typing mistakes, and color escape sequences to create a "clean" script of the procedure for future reference. Simple ASCII text preferred. I think this is what is intended by "human readable", and it is a very reasonable thing to do.

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