tau_compiler: 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 Debian possible default full paths are:

/usr/bin/tau_compiler - from package: tau

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