liblinear-train: 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/liblinear-train - from package: liblinear-cli

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

On Debian possible default full paths are:

/usr/bin/liblinear-train - from package: liblinear-tools

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

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