lcov: 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/lcov - from package: lcov

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

On Debian possible default full paths are:

/usr/bin/lcov - from package: lcov

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

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