cxxtestgen: 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
/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/cxxtestgen - from package: cxxtest

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

On Debian possible default full paths are:

/usr/bin/cxxtestgen - from package: cxxtest

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