condor_on: 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/condor_on - from package: condor

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

On Debian possible default full paths are:

/usr/sbin/condor_on - from package: htcondor

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

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