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