stg: 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/stg - from package: stgit

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

On Debian possible default full paths are:

/usr/bin/stg - from package: stgit

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

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