scilab: 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/scilab - from package: scilab
/var/lib/wims/public_html/bin/scilab - from package: wims

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

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