ols: 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/ols - from package: speech-tools

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

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