c89: 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/c89 - from package: gcc

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

Error in other languages:
c89: bevel nie gevind nie
c89: comandă negăsită
c89: comando não encontrado
c89: commande introuvable
c89: command not found
c89: käsku ei ole
c89: không tìm thấy lệnh
c89: komanda nerasta
c89: Kommando nicht gefunden.
c89: kommandot finns inte
c89: komut yok
c89: nie znaleziono polecenia
c89: níor aimsíodh an t-ordú
c89: no se encontró la orden
c89: no s'ha trobat l'ordre
c89: opdracht niet gevonden
c89: parancs nem található
c89: perintah tidak ditemukan
c89: príkaz nenájdený
c89: příkaz nenalezen
c89: команда не найдена
c89: командата не е открита
c89: 命令找不到
c89: コマンドが見つかりません