keyhead: 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/keyhead - from package: wcstools

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

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