tabbed.default: 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/tabbed.default - from package: suckless-tools

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

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