ctfmerge: 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/ctfmerge - from package: ctfutils

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

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