deepgrep: 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/deepgrep - from package: strigi

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

On Debian possible default full paths are:

/usr/bin/deepgrep - from package: strigi-utils

You may install the required package with command apt-get install {package}

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