shar: 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/shar - from package: sharutils

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

On Debian possible default full paths are:

/usr/bin/shar - from package: sharutils

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

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