Can I programmatically “burn in” ANSI control codes to a file using unix utils?

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To display a file that contains ANSI sequences,

less -r typescript

Or,

less -R typescript

To remove ANSI and backspace sequences from a file, creating a clean newfile, try:

sed -r ':again; s/[^\x08]\x08\x1b\[K//; t again; s/\x1b_[^\x1b]*\x1b[\]//g; s/\x1B\[[^m]*m//g' typescript >newfile

How it works

  • -r

    This turns on extended regular expressions. (On BSD systems, -r should be replaced with -E. Modern versions of GNU sed will accept either -r or -E.)

  • `:again; s/[^\x08]\x08\x1b[K//; t again

    This removes any backspace sequences. These are done one at a time in a loop.

  • s/\x1b_[^\x1b]*\x1b[\]//g

    As an xterm extension (see documentation), Esc _ something Esc \ will do nothing. This command removes these sequences.

  • s/\x1B\[[^m]*m//g

    This removes the remaining ANSI sequences which set colors, etc.

This covers all the control sequences that I normally run into. There are a wide variety of extended control sequences and, if your output has some that I haven’t seen, the code may need to be extended.

POSIX or BSD sed

On a BSD or POSIX system, individual commands have to be chained together with -e options instead of semicolons. Thus, try:

sed -e ':again' -e 's/[^\x08]\x08\x1b\[K//' -e 't again' -e 's/\x1b_[^\x1b]*\x1b[\]//g' -e 's/\x1B\[[^m]*m//g'

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