col9: 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/col9 - from package: byobu

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

Error in other languages:
col9: bevel nie gevind nie
col9: comandă negăsită
col9: comando não encontrado
col9: commande introuvable
col9: command not found
col9: käsku ei ole
col9: không tìm thấy lệnh
col9: komanda nerasta
col9: Kommando nicht gefunden.
col9: kommandot finns inte
col9: komut yok
col9: nie znaleziono polecenia
col9: níor aimsíodh an t-ordú
col9: no se encontró la orden
col9: no s'ha trobat l'ordre
col9: opdracht niet gevonden
col9: parancs nem található
col9: perintah tidak ditemukan
col9: príkaz nenájdený
col9: příkaz nenalezen
col9: команда не найдена
col9: командата не е открита
col9: 命令找不到
col9: コマンドが見つかりません