pcapuc: 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/pcapuc - from package: pcaputils

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