arcsub: 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/bin/arcsub - from package: nordugrid-arc-client

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

On Debian possible default full paths are:

/usr/bin/arcsub - from package: nordugrid-arc-client

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

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