opj_dump: 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/opj_dump - from package: libopenjp2-tools

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

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