sikuli: 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/sikuli - from package: libsikuli-script-java

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

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