psftp: 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/psftp - from package: putty

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

On Debian possible default full paths are:

/usr/bin/psftp - from package: putty-tools

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

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