[root@han ~]# df -h /var
S.ficheros          Tamaño Usado  Disp Uso% Montado en
/dev/sdb1              68G   21G   44G  32% /var


[root@saiph ~]# df -h /var
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol02
                       48G  428M   45G   1% /var
[root@saiph ~]# df -h /var | tail -1 | awk '{print $2}'
428M