nsca: 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/nsca - from package: nsca

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

On Debian possible default full paths are:

/usr/sbin/nsca - from package: nsca

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

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