param_chooser: 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/seqan/bin/param_chooser - from package: seqan-apps

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

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