checksub: 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/checksub - from package: ncbi-tools-bin

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

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