idevicepair: 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 Debian possible default full paths are:

/usr/bin/idevicepair - from package: libimobiledevice-utils

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

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