sselp: 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/sselp - from package: sselp

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

On Debian possible default full paths are:

/usr/bin/sselp - from package: suckless-tools

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

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