maskfeat: 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/maskfeat - from package: emboss

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

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