gethead: 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/gethead - from package: wcstools

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

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