Rd2pdf: 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/Rd2pdf - from package: R-core
/usr/lib/R/bin/Rd2pdf - 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/Rd2pdf - from package: r-base-core

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

Error in other languages:
Rd2pdf: bevel nie gevind nie
Rd2pdf: comandă negăsită
Rd2pdf: comando não encontrado
Rd2pdf: commande introuvable
Rd2pdf: command not found
Rd2pdf: käsku ei ole
Rd2pdf: không tìm thấy lệnh
Rd2pdf: komanda nerasta
Rd2pdf: Kommando nicht gefunden.
Rd2pdf: kommandot finns inte
Rd2pdf: komut yok
Rd2pdf: nie znaleziono polecenia
Rd2pdf: níor aimsíodh an t-ordú
Rd2pdf: no se encontró la orden
Rd2pdf: no s'ha trobat l'ordre
Rd2pdf: opdracht niet gevonden
Rd2pdf: parancs nem található
Rd2pdf: perintah tidak ditemukan
Rd2pdf: príkaz nenájdený
Rd2pdf: příkaz nenalezen
Rd2pdf: команда не найдена
Rd2pdf: командата не е открита
Rd2pdf: 命令找不到
Rd2pdf: コマンドが見つかりません