sed gzipped files

[Ken Tiernan]

Greetings,

Our vendors tech support person executed sed "s/$/6|/" filename.gz and screwed up some files.

Does anyone know how I can reverse sed changes to a gzipped file?

Regards,

Ken

[James R. Ferguson]

Hi Ken:

How about a restore from backup...

Regards!

...JRF...

[harry d brown jr]

If all they did was

sed "s/$/6|/" filename.gz

then the output was sent to the terminal and not to a file.

Was it something else they did??


live free or die
harry

[Ken Tiernan]

I wish these people would follow the back it up before you screw it up rule, but...

Anyway, they ran a script that had a line like this:

sed "s/$/6|/" ${file} > ${file}.new
mv ${file}.new ${file}

or this:

sed "s/366|6|$/6|/" ${file} > ${file}.new
mv ${file}.new ${file}

The files that were altered were already gzipped, so the sed command corrupted the files, but I am hoping there is a way to reverse what was done.

[A. Clay Stephenson]

Unfortunately, there is no way to reliably reverse this process because one can't be assurred that the replacement pattern was not already in the original data. Moreover, running sed on non-text data is fraught with peril. It's time to restore from backup and break out the baseball bat - not necessarily in that order.

[harry d brown jr]

Ken,

I agree with JRF and CLAY, the files are TOAST. I ran the test myself and found that the "sed' removed the null strings from the file, rendering the files useless and unrecoverable. Unrecoverable, unless you are the nsa or CIA :-)

Get a Lawyer, get a company!

I'd persuade them that they owe you some SYSTEM upgrades, free software, new car, boat, hot tub, ... whatever your heart desires :-)


live free or die
harry

[Wodisch_1]

Hi Ken,

well, assuming that those files are IMPORTANT, and that you have endless resources at hand (like time, and diskspace), you could write a script which would - for each and every file - re-substitute one "6|" at line ends after another, then run "gzip -t" on it, to check wether it is consistent, then. Of course you will have to do that for all COMBINATIONS af resubstitutions and not-substitutions, so it will take endless hours...
And "sed" might have deleted" some characters in addition, like zero-bytes - then you are truely lost :-(

But before you do antyhing, get proof that you are NOT the guilty guy! Make them confess on paper, safe and print their ".*history" files or such...

Paranoids live longer,
Wodisch