stag-mogrify: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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-mogrify - from package: libdata-stag-perl

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