delve: 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/delve - from package: xapian-core

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

On Debian possible default full paths are:

/usr/bin/delve - from package: xapian-tools

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

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