stest: 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

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/stest - from package: suckless-tools

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