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

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

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