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

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