fzsftp: 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 CentOS possible default full paths are:

/usr/bin/fzsftp - from package: filezilla

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/fzsftp - from package: filezilla

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

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