rcsfreeze: 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/rcsfreeze - from package: rcs

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

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