gunicorn_paster: command not found

Have You tried accessing the binary with the full path?

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/gunicorn_paster - from package: python-gunicorn

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

On Debian possible default full paths are:

/usr/bin/gunicorn_paster - from package: gunicorn

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