incrontab: 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/incrontab - from package: incron

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

On Debian possible default full paths are:

/usr/bin/incrontab - from package: incron

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

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