fossil: 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/fossil - from package: fossil

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

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