gettab: 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/gettab - from package: wcstools

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

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