dmesgt

#!/bin/bash
#
# Code from https://stackoverflow.com/a/36361197/4640820 by Allen Belletti
# based itself on code from https://stackoverflow.com/a/19272272/4640820 by Lucas Cimon
#

help() {
   echo 'usage: dmesgt'
   echo '       dmesgt --help'
   echo
   echo '    Output dmesg with not broken timestamps.'
   echo
   exit 1
}

[ "$1" == "--help" ] && help

set -e          # stop on error
set -u          # stop on undefined variable
set -o pipefail # stop part of pipeline failing

FORMAT="%a %b %d %H:%M:%S %Y"

now=$(date +%s)
cputime_line=$(grep -m1 "\.clock" /proc/sched_debug)

if [[ $cputime_line =~ [^0-9]*([0-9]*).* ]]; then
    cputime=$((BASH_REMATCH[1] / 1000))
fi

dmesg | while IFS= read -r line; do
    if [[ $line =~ ^\[\ *([0-9]+)\.[0-9]+\]\ (.*) ]]; then
        stamp=$((now-cputime+BASH_REMATCH[1]))
        echo "[$(date +"${FORMAT}" --date=@${stamp})] ${BASH_REMATCH[2]}"
    else
        echo "$line"
    fi
done