sysinfo.gap: 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/bin/sysinfo.gap - from package: gap-dev

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

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