arcproxyalt: command not found

Have You tried accessing the binary with the full path?

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/arcproxyalt - from package: nordugrid-arc-arcproxyalt

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

On Debian possible default full paths are:

/usr/bin/arcproxyalt - from package: nordugrid-arc-arcproxyalt
/usr/lib/debug/usr/bin/arcproxyalt - from package: nordugrid-arc-dbg

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