grid-default-ca: 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/grid-default-ca - from package: globus-gsi-cert-utils-progs

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

On Debian possible default full paths are:

/usr/sbin/grid-default-ca - from package: globus-gsi-cert-utils-progs

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

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