djvutoxml: 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/djvutoxml - from package: djvulibre

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

On Debian possible default full paths are:

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

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

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