otclsh: 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/otclsh - from package: otcl-shells

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

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