t:lustre-release# lfs df /tmp
t:lustre-release# echo $?
0
t:lustre-release# lfs df /mnt/lustre XXX
UUID                   1K-blocks        Used   Available Use% Mounted on
lustre-MDT0000_UUID       141752       19528      112864  15% /mnt/lustre[MDT:0]
lustre-OST0000_UUID       366744       29892      317380   9% /mnt/lustre[OST:0]
lustre-OST0001_UUID       366744       29892      317352   9% /mnt/lustre[OST:1]

filesystem_summary:       733488       59784      634732   9% /mnt/lustre

t:lustre-release# echo $?
0
t:lustre-release# lfs df XXX /mnt/lustre
error: invalid path 'XXX': No such file or directory
t:lustre-release# echo $?
2