tc2null: 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/tc2null - from package: troffcvt

You may install the required package with command apt-get install {package}
Error in other languages:
tc2null: bevel nie gevind nie
tc2null: comandă negăsită
tc2null: comando não encontrado
tc2null: commande introuvable
tc2null: command not found
tc2null: käsku ei ole
tc2null: không tìm thấy lệnh
tc2null: komanda nerasta
tc2null: Kommando nicht gefunden.
tc2null: kommandot finns inte
tc2null: komut yok
tc2null: nie znaleziono polecenia
tc2null: níor aimsíodh an t-ordú
tc2null: no se encontró la orden
tc2null: no s'ha trobat l'ordre
tc2null: opdracht niet gevonden
tc2null: parancs nem található
tc2null: perintah tidak ditemukan
tc2null: príkaz nenájdený
tc2null: příkaz nenalezen
tc2null: команда не найдена
tc2null: командата не е открита
tc2null: 命令找不到
tc2null: コマンドが見つかりません