grid-ca-create: 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/grid-ca-create - from package: globus-simple-ca

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

On Debian possible default full paths are:

/usr/bin/grid-ca-create - from package: globus-simple-ca

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

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