perldoc: 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/perldoc - from package: perl

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

On Debian possible default full paths are:

/usr/bin/perldoc - from package: perl-doc
/usr/bin/perldoc - from package: perl

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

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