onig-config: 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/onig-config - from package: oniguruma-devel

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

On Debian possible default full paths are:

/usr/bin/onig-config - from package: libonig-dev

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

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