latexdiff-git: 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/latexdiff-git - from package: latexdiff

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

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