yshift: 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/yshift - from package: patchy

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

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