icesh: 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 CentOS possible default full paths are:

/usr/bin/icesh - from package: icewm

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/icesh - from package: icewm

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

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