gahp_server: 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/gahp_server - from package: condor

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

On Debian possible default full paths are:

/usr/sbin/gahp_server - from package: htcondor

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

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