genhtml: 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/genhtml - from package: lcov

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

On Debian possible default full paths are:

/usr/bin/genhtml - from package: lcov

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

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