rasterisk: 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 CentOS possible default full paths are:

/usr/sbin/rasterisk - from package: asterisk

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/sbin/rasterisk - from package: asterisk

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

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