qhost: 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

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/qhost - from package: gridengine
/usr/share/gridengine/bin/lx26-amd64/qhost - from package: gridengine
/usr/share/gridengine/bin/lx26-x86/qhost - from package: gridengine

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