runant.py: 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/runant.py - from package: ant-scripts
/usr/lib64/eclipse/plugins/org.apache.ant_1.7.1.v20100518-1145/bin/runant.py - from package: eclipse-platform

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

On Debian possible default full paths are:

/usr/lib/eclipse/plugins/org.apache.ant_1.8.3.v20120321-1730/bin/runant.py - from package: eclipse-platform-data
/usr/share/eclipse/plugins/org.apache.ant_1.8.3.v20120321-1730/bin/runant.py - from package: eclipse-platform-data

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

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