qmake: 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/share/gridengine/bin/lx26-amd64/qmake - from package: gridengine
/usr/share/gridengine/bin/lx26-x86/qmake - from package: gridengine
/usr/lib64/qt-3.3/bin/qmake - from package: qt3-devel
/usr/lib/qt-3.3/bin/qmake - from package: qt3-devel
/usr/lib64/qt5/bin/qmake - from package: qt5-qtbase-devel
/usr/lib/qt5/bin/qmake - from package: qt5-qtbase-devel
/usr/lib64/qt4/bin/qmake - from package: qt-devel
/usr/lib/qt4/bin/qmake - from package: qt-devel

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

On Debian possible default full paths are:

/usr/lib/x86_64-linux-gnu/qt4/bin/qmake - from package: qt4-qmake
/usr/share/qt4/bin/qmake - from package: qt4-qmake
/usr/lib/x86_64-linux-gnu/qt5/bin/qmake - from package: qt5-qmake
/usr/bin/qmake - from package: qtchooser

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

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