colored_dmesg: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/colored_dmesg - from package: libterm-extendedcolor-perl

You may install the required package with command apt-get install {package}

Error in other languages:
colored_dmesg: bevel nie gevind nie
colored_dmesg: comandă negăsită
colored_dmesg: comando não encontrado
colored_dmesg: commande introuvable
colored_dmesg: command not found
colored_dmesg: käsku ei ole
colored_dmesg: không tìm thấy lệnh
colored_dmesg: komanda nerasta
colored_dmesg: Kommando nicht gefunden.
colored_dmesg: kommandot finns inte
colored_dmesg: komut yok
colored_dmesg: nie znaleziono polecenia
colored_dmesg: níor aimsíodh an t-ordú
colored_dmesg: no se encontró la orden
colored_dmesg: no s'ha trobat l'ordre
colored_dmesg: opdracht niet gevonden
colored_dmesg: parancs nem található
colored_dmesg: perintah tidak ditemukan
colored_dmesg: príkaz nenájdený
colored_dmesg: příkaz nenalezen
colored_dmesg: команда не найдена
colored_dmesg: командата не е открита
colored_dmesg: 命令找不到
colored_dmesg: コマンドが見つかりません