clang-modernize-3.4: 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

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 Debian possible default full paths are:

/usr/bin/clang-modernize-3.4 - from package: clang-modernize-3.4

You may install the required package with command apt-get install {package}
Error in other languages:
clang-modernize-3.4: bevel nie gevind nie
clang-modernize-3.4: comandă negăsită
clang-modernize-3.4: comando não encontrado
clang-modernize-3.4: commande introuvable
clang-modernize-3.4: command not found
clang-modernize-3.4: käsku ei ole
clang-modernize-3.4: không tìm thấy lệnh
clang-modernize-3.4: komanda nerasta
clang-modernize-3.4: Kommando nicht gefunden.
clang-modernize-3.4: kommandot finns inte
clang-modernize-3.4: komut yok
clang-modernize-3.4: nie znaleziono polecenia
clang-modernize-3.4: níor aimsíodh an t-ordú
clang-modernize-3.4: no se encontró la orden
clang-modernize-3.4: no s'ha trobat l'ordre
clang-modernize-3.4: opdracht niet gevonden
clang-modernize-3.4: parancs nem található
clang-modernize-3.4: perintah tidak ditemukan
clang-modernize-3.4: príkaz nenájdený
clang-modernize-3.4: příkaz nenalezen
clang-modernize-3.4: команда не найдена
clang-modernize-3.4: командата не е открита
clang-modernize-3.4: 命令找不到
clang-modernize-3.4: コマンドが見つかりません