rcsmerge: 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/rcsmerge - from package: rcs

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

On Debian possible default full paths are:

/usr/bin/rcsmerge - from package: rcs

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

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