fastalength: 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 CentOS possible default full paths are:

/usr/bin/fastalength - from package: exonerate

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/fastalength - from package: exonerate

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

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