fnrancid: 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/lib/rancid/bin/fnrancid - from package: rancid

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

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