kshell: 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 CentOS possible default full paths are:

/usr/bin/kshell - from package: kdelibs3

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