Rcmd: 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/lib64/R/bin/Rcmd - from package: R-core
/usr/lib/R/bin/Rcmd - from package: R-core

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

On Debian possible default full paths are:

/usr/lib/R/bin/Rcmd - from package: r-base-core

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

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