lshell: 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/lshell - from package: lshell

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

On Debian possible default full paths are:

/usr/bin/lshell - from package: lshell

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

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