gjavah-4.8: 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/gjavah-4.8 - from package: gcj-4.8-jdk

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

Error in other languages:
gjavah-4.8: bevel nie gevind nie
gjavah-4.8: comandă negăsită
gjavah-4.8: comando não encontrado
gjavah-4.8: commande introuvable
gjavah-4.8: command not found
gjavah-4.8: käsku ei ole
gjavah-4.8: không tìm thấy lệnh
gjavah-4.8: komanda nerasta
gjavah-4.8: Kommando nicht gefunden.
gjavah-4.8: kommandot finns inte
gjavah-4.8: komut yok
gjavah-4.8: nie znaleziono polecenia
gjavah-4.8: níor aimsíodh an t-ordú
gjavah-4.8: no se encontró la orden
gjavah-4.8: no s'ha trobat l'ordre
gjavah-4.8: opdracht niet gevonden
gjavah-4.8: parancs nem található
gjavah-4.8: perintah tidak ditemukan
gjavah-4.8: príkaz nenájdený
gjavah-4.8: příkaz nenalezen
gjavah-4.8: команда не найдена
gjavah-4.8: командата не е открита
gjavah-4.8: 命令找不到
gjavah-4.8: コマンドが見つかりません