wifichoice.sh: 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:

/sbin/wifichoice.sh - from package: ifscheme

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

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