powerline: 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 Debian possible default full paths are:

/usr/bin/powerline - from package: powerline

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

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