ibmssh: 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/ibmssh - from package: ibutils

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

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