rcs: 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/rcs - from package: rcs

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

On Debian possible default full paths are:

/usr/bin/rcs - from package: rcs

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

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