zabbix_proxy_sqlite3: 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/sbin/zabbix_proxy_sqlite3 - from package: zabbix20-proxy-sqlite3
/usr/sbin/zabbix_proxy_sqlite3 - from package: zabbix22-proxy-sqlite3
/usr/sbin/zabbix_proxy_sqlite3 - from package: zabbix-proxy-sqlite3

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

Error in other languages:
zabbix_proxy_sqlite3: bevel nie gevind nie
zabbix_proxy_sqlite3: comandă negăsită
zabbix_proxy_sqlite3: comando não encontrado
zabbix_proxy_sqlite3: commande introuvable
zabbix_proxy_sqlite3: command not found
zabbix_proxy_sqlite3: käsku ei ole
zabbix_proxy_sqlite3: không tìm thấy lệnh
zabbix_proxy_sqlite3: komanda nerasta
zabbix_proxy_sqlite3: Kommando nicht gefunden.
zabbix_proxy_sqlite3: kommandot finns inte
zabbix_proxy_sqlite3: komut yok
zabbix_proxy_sqlite3: nie znaleziono polecenia
zabbix_proxy_sqlite3: níor aimsíodh an t-ordú
zabbix_proxy_sqlite3: no se encontró la orden
zabbix_proxy_sqlite3: no s'ha trobat l'ordre
zabbix_proxy_sqlite3: opdracht niet gevonden
zabbix_proxy_sqlite3: parancs nem található
zabbix_proxy_sqlite3: perintah tidak ditemukan
zabbix_proxy_sqlite3: príkaz nenájdený
zabbix_proxy_sqlite3: příkaz nenalezen
zabbix_proxy_sqlite3: команда не найдена
zabbix_proxy_sqlite3: командата не е открита
zabbix_proxy_sqlite3: 命令找不到
zabbix_proxy_sqlite3: コマンドが見つかりません