myproxy-retrieve: 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/myproxy-retrieve - from package: myproxy

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

On Debian possible default full paths are:

/usr/bin/myproxy-retrieve - from package: myproxy

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

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