How to write stdout to file with colors?

Question

A lot of times (not always) the stdout is displayed in colors. Normally I keep every output log in a different file too. Naturally in the file, the colors are not displayed anymore.

I'd like to know if there's a way (in Linux) to write the output to a file with colors. I'm trying to use tee to write the output of vagrant to a file, this way I can still see the output (when it applies). I want to use it specifically for vagrant (it may change in the future, of course...)

Answer 1

Since many programs will only output color sequences if their stdout is a terminal, a general solution to this problem requires tricking them into believing that the pipe they write to is a terminal. This is possible with the script command from bsdutils:

script -q -c "vagrant up" filename.txt 

This will write the output from vagrant up to filename.txt (and the terminal). If echoing is not desirable,

script -q -c "vagrant up" filename > /dev/null 

will write it only to the file.

Answer 2

You can save the ANSI sequences that colourise your output to a file:

echo a | grep --color=always . > colour.txt
cat colour.txt

Some programs, though, tend not to use them if their output doesn't go to the terminal (that's why I had to use --color-always with grep).

Answer 3

You can also color your output with echo with different colours and save the coloured output in file. Example

echo -e '\E[37;44m'"Hello World" > my_file

Also You would have to be acquainted with the terminal colour codes

Using tee

< command line > |tee -a 'my_colour_file'

Open your file in cat

cat 'my_colour_file'

Using a named pipe can also work to redirect all output from the pipe with colors to another file

for example

Create a named pipe

mkfifo pipe.fifo

each command line redirect it to the pipe as follows

<command line> > pipe.fifo

In another terminal redirect all messages from the pipe to your file

cat pipe.fifo > 'my_log_file_with_colours'

open your file with cat and see the expected results.