ulimit.sh: 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/mediawiki119/bin/ulimit.sh - from package: mediawiki119

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

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