optimize2bw: 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/optimize2bw - from package: exactimage

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

Error in other languages:
optimize2bw: bevel nie gevind nie
optimize2bw: comandă negăsită
optimize2bw: comando não encontrado
optimize2bw: commande introuvable
optimize2bw: command not found
optimize2bw: käsku ei ole
optimize2bw: không tìm thấy lệnh
optimize2bw: komanda nerasta
optimize2bw: Kommando nicht gefunden.
optimize2bw: kommandot finns inte
optimize2bw: komut yok
optimize2bw: nie znaleziono polecenia
optimize2bw: níor aimsíodh an t-ordú
optimize2bw: no se encontró la orden
optimize2bw: no s'ha trobat l'ordre
optimize2bw: opdracht niet gevonden
optimize2bw: parancs nem található
optimize2bw: perintah tidak ditemukan
optimize2bw: príkaz nenájdený
optimize2bw: příkaz nenalezen
optimize2bw: команда не найдена
optimize2bw: командата не е открита
optimize2bw: 命令找不到
optimize2bw: コマンドが見つかりません