synaesthesia: 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/synaesthesia - from package: synaesthesia

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

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