col4: 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/col4 - from package: byobu

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

Error in other languages:
col4: bevel nie gevind nie
col4: comandă negăsită
col4: comando não encontrado
col4: commande introuvable
col4: command not found
col4: käsku ei ole
col4: không tìm thấy lệnh
col4: komanda nerasta
col4: Kommando nicht gefunden.
col4: kommandot finns inte
col4: komut yok
col4: nie znaleziono polecenia
col4: níor aimsíodh an t-ordú
col4: no se encontró la orden
col4: no s'ha trobat l'ordre
col4: opdracht niet gevonden
col4: parancs nem található
col4: perintah tidak ditemukan
col4: príkaz nenájdený
col4: příkaz nenalezen
col4: команда не найдена
col4: командата не е открита
col4: 命令找不到
col4: コマンドが見つかりません