csgrep: 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/csgrep - from package: csdiff

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

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