Ubuntu Link to Learn it

[Robert Fraley]

Hello,
I am a new Linux user and have a new build just assembled. I have a working Ubuntu OS on my new PC and have to learn how to use it. I have not added programs to use for Internet downloads. For instance I was trying to open up a download and got an error message. " end of directorysignature not found. ..."

Any links helpful to learn how to use it? THanks

 

[skittle]

your download is probably corrupted. Re-download, and check MD5 or SHA-1 sum...

 

[Robert Fraley]

Best answer selected by robert fraley.

 

[Robert Fraley]

thanks for the response. I have no idea what that means, though.

 

[Robert Fraley]

I will try a new download in the meantime.

 

[bmouring]

Basically, if the file you are downloading is large, there's a greater-than-zero chance that part of the download is corrupted (essentially, if during the period of download, you receive more that 2^32 packets and there is some agent in the connection that tends to cause bit errors, chances are you will have a checksum collision, or an undetected corruption).

Some sources for larger downloads (e.g. Linux DVD ISOs) will provide MD5 and/or SHA(128|256) "hashes" for the file you are downloading. Essentially, once you've completed the download, you use a tool (like this for either type and many more). Run the tool on your download and ensure that the resulting number (it will be a hexidecimal number) matches what is indicated by the download source.

Hashes have the property that a slight difference between two file will result in (with a high level of probability) wildly-different hashes, so it should be pretty easy to spot differences if there was a corruption in downloading. As an example:

brad@onyx:~$ echo "this is a test" > test1
brad@onyx:~$ echo "this is a tess" > test2
brad@onyx:~$ sha256sum test1 
91751cee0a1ab8414400238a761411daa29643ab4b8243e9a91649e25be53ada  test1
brad@onyx:~$ sha256sum test2
f099c90317b882b7139a9f3c81387889042353ebdfe998e2360b92b4cae499a5  test2

If your download source does not provide a hash for comparison, you could simply attempt to re-download it and compare the hashes of the two files

 

[audiovoodoo]

Just to expand on the good advice from bmouring there is a very good guide to md5sum operation on the Ubuntu help site:

https://help.ubuntu.com/community/HowToMD5SUM

Follow it through and hopefully it will clear up any confusion.

 

[Robert Fraley]

Ok, thank you guys But my system does work online. I have been able to go online with the cd running. I ran it installed on the hard drive also. So, I have just to look at the setup or the BIOS maybe. I know it works. It just needs to be starting properly. Somehow, I think it is BIOS. My system is using UEFI BIOS and it has a lot of options.