gmk_sym: 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/gmk_sym - from package: geda-utils

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

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