polipo: 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/polipo - from package: polipo

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

On Debian possible default full paths are:

/usr/bin/polipo - from package: polipo

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

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