gsislogin: 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/gsislogin - from package: gsi-openssh-clients

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

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