gtags: 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/gtags - from package: global

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

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