linux - Difference between df -k and du -sh

df -k
/dev/sda6             25396228  21249088   2836240  89% /export
21G used

versus

du -sh /export 
3.4G    /export

The 3.4G is correct because we have removed all non essential file but free space reported by df is not consistent with the actual free space that should be there.

Why is this so?

Answer

The files you removed are probably still opened by a process. Check:

lsof -a +L1 /export

I think this is because:

• df checks blocks available (superblocks)


• du totals up the space of each file.