icu.ini: 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/share/php/Symfony/Component/Intl/Resources/bin/icu.ini - from package: php-symfony-intl

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

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