cxref-cpp.upstream: 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/cxref-cpp.upstream - from package: cxref

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