arista-gtk: 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/arista-gtk - from package: arista

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