fixcvsdiff: 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:

/usr/bin/fixcvsdiff - from package: patchutils

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

On Debian possible default full paths are:

/usr/bin/fixcvsdiff - from package: patchutils

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

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