psh: 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/lib/picolisp/bin/psh - from package: picolisp

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

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