djvutxt: 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/djvutxt - from package: djvulibre

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

On Debian possible default full paths are:

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

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

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