fastacomposition: 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/fastacomposition - from package: exonerate

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

On Debian possible default full paths are:

/usr/bin/fastacomposition - from package: exonerate

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

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