avicat: command not found

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/avicat - from package: libavifile-0.7-bin

You may install the required package with command apt-get install {package}

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