fasta_nucleotide_changer: 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/fasta_nucleotide_changer - from package: fastx-toolkit

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

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