unshar: 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/unshar - from package: sharutils

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

On Debian possible default full paths are:

/usr/bin/unshar - from package: sharutils

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

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