djvudump: 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 CentOS possible default full paths are:

/usr/bin/djvudump - from package: djvulibre

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/djvudump - from package: djvulibre-bin

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

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