col7: 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/col7 - from package: byobu

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

Error in other languages:
col7: bevel nie gevind nie
col7: comandă negăsită
col7: comando não encontrado
col7: commande introuvable
col7: command not found
col7: käsku ei ole
col7: không tìm thấy lệnh
col7: komanda nerasta
col7: Kommando nicht gefunden.
col7: kommandot finns inte
col7: komut yok
col7: nie znaleziono polecenia
col7: níor aimsíodh an t-ordú
col7: no se encontró la orden
col7: no s'ha trobat l'ordre
col7: opdracht niet gevonden
col7: parancs nem található
col7: perintah tidak ditemukan
col7: príkaz nenájdený
col7: příkaz nenalezen
col7: команда не найдена
col7: командата не е открита
col7: 命令找不到
col7: コマンドが見つかりません