rancid-fe: 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 CentOS possible default full paths are:

/usr/bin/rancid-fe - from package: rancid

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/lib/rancid/bin/rancid-fe - from package: rancid

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

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