stag-grep: 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 Debian possible default full paths are:

/usr/bin/stag-grep - from package: libdata-stag-perl

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

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