icesh-experimental: command not found

Have You tried accessing the binary with the full path?

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/icesh-experimental - from package: icewm-experimental

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