gunzip: 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:

/bin/gunzip - from package: gzip
/usr/bin/gunzip - from package: gzip

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

On Debian possible default full paths are:

/bin/gunzip - from package: gzip
/usr/lib/klibc/bin/gunzip - from package: klibc-utils

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

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