sushi: 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

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/sushi - from package: gnome-sushi

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