gapi2-fixup: 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/gapi2-fixup - from package: gtk-sharp2-gapi

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

Error in other languages:
gapi2-fixup: bevel nie gevind nie
gapi2-fixup: comandă negăsită
gapi2-fixup: comando não encontrado
gapi2-fixup: commande introuvable
gapi2-fixup: command not found
gapi2-fixup: käsku ei ole
gapi2-fixup: không tìm thấy lệnh
gapi2-fixup: komanda nerasta
gapi2-fixup: Kommando nicht gefunden.
gapi2-fixup: kommandot finns inte
gapi2-fixup: komut yok
gapi2-fixup: nie znaleziono polecenia
gapi2-fixup: níor aimsíodh an t-ordú
gapi2-fixup: no se encontró la orden
gapi2-fixup: no s'ha trobat l'ordre
gapi2-fixup: opdracht niet gevonden
gapi2-fixup: parancs nem található
gapi2-fixup: perintah tidak ditemukan
gapi2-fixup: príkaz nenájdený
gapi2-fixup: příkaz nenalezen
gapi2-fixup: команда не найдена
gapi2-fixup: командата не е открита
gapi2-fixup: 命令找不到
gapi2-fixup: コマンドが見つかりません