latexdiff-vc: 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-vc - from package: latexdiff

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

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