tiff2pdf: 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:

/var/spool/hylafax/bin/tiff2pdf - from package: hylafax+-client
/usr/bin/tiff2pdf - from package: libtiff

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

On Debian possible default full paths are:

/var/spool/hylafax/bin/tiff2pdf - from package: hylafax-server
/usr/bin/tiff2pdf - from package: libtiff-tools

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

Error in other languages:
tiff2pdf: bevel nie gevind nie
tiff2pdf: comandă negăsită
tiff2pdf: comando não encontrado
tiff2pdf: commande introuvable
tiff2pdf: command not found
tiff2pdf: käsku ei ole
tiff2pdf: không tìm thấy lệnh
tiff2pdf: komanda nerasta
tiff2pdf: Kommando nicht gefunden.
tiff2pdf: kommandot finns inte
tiff2pdf: komut yok
tiff2pdf: nie znaleziono polecenia
tiff2pdf: níor aimsíodh an t-ordú
tiff2pdf: no se encontró la orden
tiff2pdf: no s'ha trobat l'ordre
tiff2pdf: opdracht niet gevonden
tiff2pdf: parancs nem található
tiff2pdf: perintah tidak ditemukan
tiff2pdf: príkaz nenájdený
tiff2pdf: příkaz nenalezen
tiff2pdf: команда не найдена
tiff2pdf: командата не е открита
tiff2pdf: 命令找不到
tiff2pdf: コマンドが見つかりません