icewm-session-lite: 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/icewm-session-lite - from package: icewm-lite

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