gmic: 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/gmic - from package: gmic

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

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