djpeg: 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/djpeg - from package: libjpeg-turbo

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

On Debian possible default full paths are:

/usr/bin/djpeg - from package: libjpeg-turbo-progs

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

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