setstab: 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 Debian possible default full paths are:

/usr/lib/x86_64-linux-gnu/gap/pkg/guava/bin/leon/setstab - from package: gap-guava-bin

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

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