shm_askpass: 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/shm_askpass - from package: libpam-sshauth

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

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