Pager: 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/pager - from package: R-core
/usr/lib/R/bin/pager - 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/pager - from package: r-base-core
/usr/bin/Pager - from package: afterstep

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

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