gitosis-serve: 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/gitosis-serve - from package: gitosis

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

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