sigcensus: 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/bin/sigcensus - from package: regina-normal

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

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