check-ifupdown-scripts-zg2.d-symlinks: 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
/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/check-ifupdown-scripts-zg2.d-symlinks - from package: ifupdown-scripts-zg2

You may install the required package with command apt-get install {package}
Error in other languages:
check-ifupdown-scripts-zg2.d-symlinks: bevel nie gevind nie
check-ifupdown-scripts-zg2.d-symlinks: comandă negăsită
check-ifupdown-scripts-zg2.d-symlinks: comando não encontrado
check-ifupdown-scripts-zg2.d-symlinks: commande introuvable
check-ifupdown-scripts-zg2.d-symlinks: command not found
check-ifupdown-scripts-zg2.d-symlinks: käsku ei ole
check-ifupdown-scripts-zg2.d-symlinks: không tìm thấy lệnh
check-ifupdown-scripts-zg2.d-symlinks: komanda nerasta
check-ifupdown-scripts-zg2.d-symlinks: Kommando nicht gefunden.
check-ifupdown-scripts-zg2.d-symlinks: kommandot finns inte
check-ifupdown-scripts-zg2.d-symlinks: komut yok
check-ifupdown-scripts-zg2.d-symlinks: nie znaleziono polecenia
check-ifupdown-scripts-zg2.d-symlinks: níor aimsíodh an t-ordú
check-ifupdown-scripts-zg2.d-symlinks: no se encontró la orden
check-ifupdown-scripts-zg2.d-symlinks: no s'ha trobat l'ordre
check-ifupdown-scripts-zg2.d-symlinks: opdracht niet gevonden
check-ifupdown-scripts-zg2.d-symlinks: parancs nem található
check-ifupdown-scripts-zg2.d-symlinks: perintah tidak ditemukan
check-ifupdown-scripts-zg2.d-symlinks: príkaz nenájdený
check-ifupdown-scripts-zg2.d-symlinks: příkaz nenalezen
check-ifupdown-scripts-zg2.d-symlinks: команда не найдена
check-ifupdown-scripts-zg2.d-symlinks: командата не е открита
check-ifupdown-scripts-zg2.d-symlinks: 命令找不到
check-ifupdown-scripts-zg2.d-symlinks: コマンドが見つかりません