ppt2odp: command not found

Have You tried accessing the binary with the full path?

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/ppt2odp - from package: unoconv

You may install the required package with command apt-get install {package}
Error in other languages:
ppt2odp: bevel nie gevind nie
ppt2odp: comandă negăsită
ppt2odp: comando não encontrado
ppt2odp: commande introuvable
ppt2odp: command not found
ppt2odp: käsku ei ole
ppt2odp: không tìm thấy lệnh
ppt2odp: komanda nerasta
ppt2odp: Kommando nicht gefunden.
ppt2odp: kommandot finns inte
ppt2odp: komut yok
ppt2odp: nie znaleziono polecenia
ppt2odp: níor aimsíodh an t-ordú
ppt2odp: no se encontró la orden
ppt2odp: no s'ha trobat l'ordre
ppt2odp: opdracht niet gevonden
ppt2odp: parancs nem található
ppt2odp: perintah tidak ditemukan
ppt2odp: príkaz nenájdený
ppt2odp: příkaz nenalezen
ppt2odp: команда не найдена
ppt2odp: командата не е открита
ppt2odp: 命令找不到
ppt2odp: コマンドが見つかりません