[Bug-tar] Tar 1.27 has become non-deterministic

[David Barri]

Hello!

The new version of tar has become non-deterministic.

It looks like now it stores its own creation time or something internally. (?)

# 1.27

> for f in $(seq 10); do tar -cp -T filelist -f - | md5sum; done

ecaec8575b3c4609b99475c4378bdf7a  -

ecaec8575b3c4609b99475c4378bdf7a  -

ecaec8575b3c4609b99475c4378bdf7a  -

ecaec8575b3c4609b99475c4378bdf7a  -

ecaec8575b3c4609b99475c4378bdf7a  -

ecaec8575b3c4609b99475c4378bdf7a  -

ecaec8575b3c4609b99475c4378bdf7a  -

ba5400215dcec292bf807025981c8856  -  <-- change

ba5400215dcec292bf807025981c8856  -

ba5400215dcec292bf807025981c8856  -

# 1.26

> for f in $(seq 10); do tar -cp -T filelist -f - | md5sum; done 

85e65f5b675d42852c2689bfa2959467  -

85e65f5b675d42852c2689bfa2959467  -

85e65f5b675d42852c2689bfa2959467  -

85e65f5b675d42852c2689bfa2959467  -

85e65f5b675d42852c2689bfa2959467  -

85e65f5b675d42852c2689bfa2959467  -

85e65f5b675d42852c2689bfa2959467  -

85e65f5b675d42852c2689bfa2959467  -

85e65f5b675d42852c2689bfa2959467  -

85e65f5b675d42852c2689bfa2959467  -

This is a problem for me because I used to compare SHA hashes of tar files to detect change. Now my scripts constantly think content has changed.

Is this a bug? If not, is there a way to disable or manually provide this internal timestamp?

Thanks,

David