idfetch: command not found

Have You tried accessing the binary with the full path?

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/idfetch - from package: ncbi-tools-bin

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