multiple forms of sum in core utilities












3















Upon reading GNU Core Utilities - Wikipedia, I find multiple sum



me@alpha:~$ cksum nohup.out 
4104911401 101860700 nohup.out
me@alpha:~$ b2sum nohup.out
468c86394c5c4be04d0bce3b98584197b0c3f4cbb630144818f9d77d48ab7296e4c53db481b6bdd7c46dd5203d3f016d9ef01b126806e04be5003aeebb1bc6
22 nohup.out
me@alpha:~$ sum nohup.out
37767 99474
me@alpha:~$ sha1sum nohup.out
79106925d593e18bd148ba94a6e4fb9da02e8c47 nohup.out
me@alpha:~$ md5sum nohup.out
3be4b17f18e4715d849a31ae482565cf nohup.out


I started learning linux months ago, should I have to distinguish them and utilize them in daily operation?










share|improve this question



























    3















    Upon reading GNU Core Utilities - Wikipedia, I find multiple sum



    me@alpha:~$ cksum nohup.out 
    4104911401 101860700 nohup.out
    me@alpha:~$ b2sum nohup.out
    468c86394c5c4be04d0bce3b98584197b0c3f4cbb630144818f9d77d48ab7296e4c53db481b6bdd7c46dd5203d3f016d9ef01b126806e04be5003aeebb1bc6
    22 nohup.out
    me@alpha:~$ sum nohup.out
    37767 99474
    me@alpha:~$ sha1sum nohup.out
    79106925d593e18bd148ba94a6e4fb9da02e8c47 nohup.out
    me@alpha:~$ md5sum nohup.out
    3be4b17f18e4715d849a31ae482565cf nohup.out


    I started learning linux months ago, should I have to distinguish them and utilize them in daily operation?










    share|improve this question

























      3












      3








      3


      1






      Upon reading GNU Core Utilities - Wikipedia, I find multiple sum



      me@alpha:~$ cksum nohup.out 
      4104911401 101860700 nohup.out
      me@alpha:~$ b2sum nohup.out
      468c86394c5c4be04d0bce3b98584197b0c3f4cbb630144818f9d77d48ab7296e4c53db481b6bdd7c46dd5203d3f016d9ef01b126806e04be5003aeebb1bc6
      22 nohup.out
      me@alpha:~$ sum nohup.out
      37767 99474
      me@alpha:~$ sha1sum nohup.out
      79106925d593e18bd148ba94a6e4fb9da02e8c47 nohup.out
      me@alpha:~$ md5sum nohup.out
      3be4b17f18e4715d849a31ae482565cf nohup.out


      I started learning linux months ago, should I have to distinguish them and utilize them in daily operation?










      share|improve this question














      Upon reading GNU Core Utilities - Wikipedia, I find multiple sum



      me@alpha:~$ cksum nohup.out 
      4104911401 101860700 nohup.out
      me@alpha:~$ b2sum nohup.out
      468c86394c5c4be04d0bce3b98584197b0c3f4cbb630144818f9d77d48ab7296e4c53db481b6bdd7c46dd5203d3f016d9ef01b126806e04be5003aeebb1bc6
      22 nohup.out
      me@alpha:~$ sum nohup.out
      37767 99474
      me@alpha:~$ sha1sum nohup.out
      79106925d593e18bd148ba94a6e4fb9da02e8c47 nohup.out
      me@alpha:~$ md5sum nohup.out
      3be4b17f18e4715d849a31ae482565cf nohup.out


      I started learning linux months ago, should I have to distinguish them and utilize them in daily operation?







      coreutils






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked 1 hour ago









      AliceAlice

      327110




      327110






















          2 Answers
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          active

          oldest

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          1














          The checksum commands that you have found are used most often for verifying data integrity and tracking information. It's as if you solve a math problem, and then look to the answers at the end of the book to ensure that your solution is correct.



          Most common example, is when you download software or Ubuntu.iso image, you will see a file such as this (example from SHA256SUM file for 18.04 release):



          ff7feb65254b64ffadc00a3ce39df89e3cf84485343063c04fa11859475931c4 *ubuntu-18.04.1-preinstalled-server-armhf+raspi2.img.xz
          a5b0ea5918f850124f3d72ef4b85bda82f0fcd02ec721be19c1a6952791c8ee8 *ubuntu-18.04.1-server-amd64.iso
          8e9a766b4fed214632c8fd0f039c372fe18b0e5a2f4a4167f5c1edd5090385f4 *ubuntu-18.04.1-server-arm64.iso
          dc8aa1b7f9c7d7dd66bbde516e739166126faa55789da0cb63328a507ed5fc00 *ubuntu-18.04.1-server-ppc64el.iso
          76f6a384cd943a14761263b725fbccb2ebb04f147efa0c9eb884868e97c2eaac *ubuntu-18.04.1-server-s390x.iso


          When you download ubuntu-18.04.1-server-arm64.iso file, you want to ensure the file was downloaded OK, that there was no tampering with it by someone in the middle of the network, or that there was a corrupt file downloaded. Thus when you do



          sha256sum ~/Downloads/ubuntu-18.04.1-server-arm64.iso


          you will know right way if the file is OK or not. As for different types, for security applications, the stronger the has sha256 or sha512 the better, because attacker cannot break it. Hashes are one-way functions. Input produces hash, but not the other way around. So for security reasons, passwords are best never stored on servers - only hashes.



          When attackers steal information from servers, they should only have hash values of the passwords and not passwords themselves. Now, hashes such as MD5 and SHA1 have been broken and attackers can break them to find original passwords. So you don't have to memorize them, but it's good to know if an application is using a strong hash such as SHA256 or SHA512






          share|improve this answer































            4















            should I have to distinguish them and utilize them in daily operation?




            No, not really. What you have found is utilities for computing hash sums, which is used for purposes such as file verification.



            For instance, when you download a Ubuntu ISO, you will typically find a file containing a checksum, which you can verify. You download the file, and run sha256sum filename (or md5sum if it contains md5 checksums, but SHA256 is better than md5), and compare it against the published check sum.



            It also allows you to verify that a file has not changed, without having to store an duplicate of the full file. This is used by file verification tools such as tripwire.



            In general, don't worry about those utilities until you see a need for them.






            share|improve this answer


























            • "It also allows you to verify that a file has not changed, without having to store the full file." Well, files stored on local hard drive are already ... stored :) But looking at modification time in ls -l or stat output is probably faster than calculating checksum in such case . Nice answer, very concise. Have a +1

              – Sergiy Kolodyazhnyy
              17 mins ago











            • It allows you to store a small piece of data, the checksum, and not a duplicate of the file, to verify file integrity :) I agree it's a bit...weirdly worded by me :)

              – vidarlo
              11 mins ago











            • OOOOOh. OK, I've read the sentence again. Sorry, my brain foobared there. Yes, hash allows knowing that data is the same without having a duplicate copy of file to compare with to see if it changed.

              – Sergiy Kolodyazhnyy
              9 mins ago











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            1














            The checksum commands that you have found are used most often for verifying data integrity and tracking information. It's as if you solve a math problem, and then look to the answers at the end of the book to ensure that your solution is correct.



            Most common example, is when you download software or Ubuntu.iso image, you will see a file such as this (example from SHA256SUM file for 18.04 release):



            ff7feb65254b64ffadc00a3ce39df89e3cf84485343063c04fa11859475931c4 *ubuntu-18.04.1-preinstalled-server-armhf+raspi2.img.xz
            a5b0ea5918f850124f3d72ef4b85bda82f0fcd02ec721be19c1a6952791c8ee8 *ubuntu-18.04.1-server-amd64.iso
            8e9a766b4fed214632c8fd0f039c372fe18b0e5a2f4a4167f5c1edd5090385f4 *ubuntu-18.04.1-server-arm64.iso
            dc8aa1b7f9c7d7dd66bbde516e739166126faa55789da0cb63328a507ed5fc00 *ubuntu-18.04.1-server-ppc64el.iso
            76f6a384cd943a14761263b725fbccb2ebb04f147efa0c9eb884868e97c2eaac *ubuntu-18.04.1-server-s390x.iso


            When you download ubuntu-18.04.1-server-arm64.iso file, you want to ensure the file was downloaded OK, that there was no tampering with it by someone in the middle of the network, or that there was a corrupt file downloaded. Thus when you do



            sha256sum ~/Downloads/ubuntu-18.04.1-server-arm64.iso


            you will know right way if the file is OK or not. As for different types, for security applications, the stronger the has sha256 or sha512 the better, because attacker cannot break it. Hashes are one-way functions. Input produces hash, but not the other way around. So for security reasons, passwords are best never stored on servers - only hashes.



            When attackers steal information from servers, they should only have hash values of the passwords and not passwords themselves. Now, hashes such as MD5 and SHA1 have been broken and attackers can break them to find original passwords. So you don't have to memorize them, but it's good to know if an application is using a strong hash such as SHA256 or SHA512






            share|improve this answer




























              1














              The checksum commands that you have found are used most often for verifying data integrity and tracking information. It's as if you solve a math problem, and then look to the answers at the end of the book to ensure that your solution is correct.



              Most common example, is when you download software or Ubuntu.iso image, you will see a file such as this (example from SHA256SUM file for 18.04 release):



              ff7feb65254b64ffadc00a3ce39df89e3cf84485343063c04fa11859475931c4 *ubuntu-18.04.1-preinstalled-server-armhf+raspi2.img.xz
              a5b0ea5918f850124f3d72ef4b85bda82f0fcd02ec721be19c1a6952791c8ee8 *ubuntu-18.04.1-server-amd64.iso
              8e9a766b4fed214632c8fd0f039c372fe18b0e5a2f4a4167f5c1edd5090385f4 *ubuntu-18.04.1-server-arm64.iso
              dc8aa1b7f9c7d7dd66bbde516e739166126faa55789da0cb63328a507ed5fc00 *ubuntu-18.04.1-server-ppc64el.iso
              76f6a384cd943a14761263b725fbccb2ebb04f147efa0c9eb884868e97c2eaac *ubuntu-18.04.1-server-s390x.iso


              When you download ubuntu-18.04.1-server-arm64.iso file, you want to ensure the file was downloaded OK, that there was no tampering with it by someone in the middle of the network, or that there was a corrupt file downloaded. Thus when you do



              sha256sum ~/Downloads/ubuntu-18.04.1-server-arm64.iso


              you will know right way if the file is OK or not. As for different types, for security applications, the stronger the has sha256 or sha512 the better, because attacker cannot break it. Hashes are one-way functions. Input produces hash, but not the other way around. So for security reasons, passwords are best never stored on servers - only hashes.



              When attackers steal information from servers, they should only have hash values of the passwords and not passwords themselves. Now, hashes such as MD5 and SHA1 have been broken and attackers can break them to find original passwords. So you don't have to memorize them, but it's good to know if an application is using a strong hash such as SHA256 or SHA512






              share|improve this answer


























                1












                1








                1







                The checksum commands that you have found are used most often for verifying data integrity and tracking information. It's as if you solve a math problem, and then look to the answers at the end of the book to ensure that your solution is correct.



                Most common example, is when you download software or Ubuntu.iso image, you will see a file such as this (example from SHA256SUM file for 18.04 release):



                ff7feb65254b64ffadc00a3ce39df89e3cf84485343063c04fa11859475931c4 *ubuntu-18.04.1-preinstalled-server-armhf+raspi2.img.xz
                a5b0ea5918f850124f3d72ef4b85bda82f0fcd02ec721be19c1a6952791c8ee8 *ubuntu-18.04.1-server-amd64.iso
                8e9a766b4fed214632c8fd0f039c372fe18b0e5a2f4a4167f5c1edd5090385f4 *ubuntu-18.04.1-server-arm64.iso
                dc8aa1b7f9c7d7dd66bbde516e739166126faa55789da0cb63328a507ed5fc00 *ubuntu-18.04.1-server-ppc64el.iso
                76f6a384cd943a14761263b725fbccb2ebb04f147efa0c9eb884868e97c2eaac *ubuntu-18.04.1-server-s390x.iso


                When you download ubuntu-18.04.1-server-arm64.iso file, you want to ensure the file was downloaded OK, that there was no tampering with it by someone in the middle of the network, or that there was a corrupt file downloaded. Thus when you do



                sha256sum ~/Downloads/ubuntu-18.04.1-server-arm64.iso


                you will know right way if the file is OK or not. As for different types, for security applications, the stronger the has sha256 or sha512 the better, because attacker cannot break it. Hashes are one-way functions. Input produces hash, but not the other way around. So for security reasons, passwords are best never stored on servers - only hashes.



                When attackers steal information from servers, they should only have hash values of the passwords and not passwords themselves. Now, hashes such as MD5 and SHA1 have been broken and attackers can break them to find original passwords. So you don't have to memorize them, but it's good to know if an application is using a strong hash such as SHA256 or SHA512






                share|improve this answer













                The checksum commands that you have found are used most often for verifying data integrity and tracking information. It's as if you solve a math problem, and then look to the answers at the end of the book to ensure that your solution is correct.



                Most common example, is when you download software or Ubuntu.iso image, you will see a file such as this (example from SHA256SUM file for 18.04 release):



                ff7feb65254b64ffadc00a3ce39df89e3cf84485343063c04fa11859475931c4 *ubuntu-18.04.1-preinstalled-server-armhf+raspi2.img.xz
                a5b0ea5918f850124f3d72ef4b85bda82f0fcd02ec721be19c1a6952791c8ee8 *ubuntu-18.04.1-server-amd64.iso
                8e9a766b4fed214632c8fd0f039c372fe18b0e5a2f4a4167f5c1edd5090385f4 *ubuntu-18.04.1-server-arm64.iso
                dc8aa1b7f9c7d7dd66bbde516e739166126faa55789da0cb63328a507ed5fc00 *ubuntu-18.04.1-server-ppc64el.iso
                76f6a384cd943a14761263b725fbccb2ebb04f147efa0c9eb884868e97c2eaac *ubuntu-18.04.1-server-s390x.iso


                When you download ubuntu-18.04.1-server-arm64.iso file, you want to ensure the file was downloaded OK, that there was no tampering with it by someone in the middle of the network, or that there was a corrupt file downloaded. Thus when you do



                sha256sum ~/Downloads/ubuntu-18.04.1-server-arm64.iso


                you will know right way if the file is OK or not. As for different types, for security applications, the stronger the has sha256 or sha512 the better, because attacker cannot break it. Hashes are one-way functions. Input produces hash, but not the other way around. So for security reasons, passwords are best never stored on servers - only hashes.



                When attackers steal information from servers, they should only have hash values of the passwords and not passwords themselves. Now, hashes such as MD5 and SHA1 have been broken and attackers can break them to find original passwords. So you don't have to memorize them, but it's good to know if an application is using a strong hash such as SHA256 or SHA512







                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered 22 mins ago









                Sergiy KolodyazhnyySergiy Kolodyazhnyy

                71.3k9147313




                71.3k9147313

























                    4















                    should I have to distinguish them and utilize them in daily operation?




                    No, not really. What you have found is utilities for computing hash sums, which is used for purposes such as file verification.



                    For instance, when you download a Ubuntu ISO, you will typically find a file containing a checksum, which you can verify. You download the file, and run sha256sum filename (or md5sum if it contains md5 checksums, but SHA256 is better than md5), and compare it against the published check sum.



                    It also allows you to verify that a file has not changed, without having to store an duplicate of the full file. This is used by file verification tools such as tripwire.



                    In general, don't worry about those utilities until you see a need for them.






                    share|improve this answer


























                    • "It also allows you to verify that a file has not changed, without having to store the full file." Well, files stored on local hard drive are already ... stored :) But looking at modification time in ls -l or stat output is probably faster than calculating checksum in such case . Nice answer, very concise. Have a +1

                      – Sergiy Kolodyazhnyy
                      17 mins ago











                    • It allows you to store a small piece of data, the checksum, and not a duplicate of the file, to verify file integrity :) I agree it's a bit...weirdly worded by me :)

                      – vidarlo
                      11 mins ago











                    • OOOOOh. OK, I've read the sentence again. Sorry, my brain foobared there. Yes, hash allows knowing that data is the same without having a duplicate copy of file to compare with to see if it changed.

                      – Sergiy Kolodyazhnyy
                      9 mins ago
















                    4















                    should I have to distinguish them and utilize them in daily operation?




                    No, not really. What you have found is utilities for computing hash sums, which is used for purposes such as file verification.



                    For instance, when you download a Ubuntu ISO, you will typically find a file containing a checksum, which you can verify. You download the file, and run sha256sum filename (or md5sum if it contains md5 checksums, but SHA256 is better than md5), and compare it against the published check sum.



                    It also allows you to verify that a file has not changed, without having to store an duplicate of the full file. This is used by file verification tools such as tripwire.



                    In general, don't worry about those utilities until you see a need for them.






                    share|improve this answer


























                    • "It also allows you to verify that a file has not changed, without having to store the full file." Well, files stored on local hard drive are already ... stored :) But looking at modification time in ls -l or stat output is probably faster than calculating checksum in such case . Nice answer, very concise. Have a +1

                      – Sergiy Kolodyazhnyy
                      17 mins ago











                    • It allows you to store a small piece of data, the checksum, and not a duplicate of the file, to verify file integrity :) I agree it's a bit...weirdly worded by me :)

                      – vidarlo
                      11 mins ago











                    • OOOOOh. OK, I've read the sentence again. Sorry, my brain foobared there. Yes, hash allows knowing that data is the same without having a duplicate copy of file to compare with to see if it changed.

                      – Sergiy Kolodyazhnyy
                      9 mins ago














                    4












                    4








                    4








                    should I have to distinguish them and utilize them in daily operation?




                    No, not really. What you have found is utilities for computing hash sums, which is used for purposes such as file verification.



                    For instance, when you download a Ubuntu ISO, you will typically find a file containing a checksum, which you can verify. You download the file, and run sha256sum filename (or md5sum if it contains md5 checksums, but SHA256 is better than md5), and compare it against the published check sum.



                    It also allows you to verify that a file has not changed, without having to store an duplicate of the full file. This is used by file verification tools such as tripwire.



                    In general, don't worry about those utilities until you see a need for them.






                    share|improve this answer
















                    should I have to distinguish them and utilize them in daily operation?




                    No, not really. What you have found is utilities for computing hash sums, which is used for purposes such as file verification.



                    For instance, when you download a Ubuntu ISO, you will typically find a file containing a checksum, which you can verify. You download the file, and run sha256sum filename (or md5sum if it contains md5 checksums, but SHA256 is better than md5), and compare it against the published check sum.



                    It also allows you to verify that a file has not changed, without having to store an duplicate of the full file. This is used by file verification tools such as tripwire.



                    In general, don't worry about those utilities until you see a need for them.







                    share|improve this answer














                    share|improve this answer



                    share|improve this answer








                    edited 8 mins ago

























                    answered 33 mins ago









                    vidarlovidarlo

                    9,68352446




                    9,68352446













                    • "It also allows you to verify that a file has not changed, without having to store the full file." Well, files stored on local hard drive are already ... stored :) But looking at modification time in ls -l or stat output is probably faster than calculating checksum in such case . Nice answer, very concise. Have a +1

                      – Sergiy Kolodyazhnyy
                      17 mins ago











                    • It allows you to store a small piece of data, the checksum, and not a duplicate of the file, to verify file integrity :) I agree it's a bit...weirdly worded by me :)

                      – vidarlo
                      11 mins ago











                    • OOOOOh. OK, I've read the sentence again. Sorry, my brain foobared there. Yes, hash allows knowing that data is the same without having a duplicate copy of file to compare with to see if it changed.

                      – Sergiy Kolodyazhnyy
                      9 mins ago



















                    • "It also allows you to verify that a file has not changed, without having to store the full file." Well, files stored on local hard drive are already ... stored :) But looking at modification time in ls -l or stat output is probably faster than calculating checksum in such case . Nice answer, very concise. Have a +1

                      – Sergiy Kolodyazhnyy
                      17 mins ago











                    • It allows you to store a small piece of data, the checksum, and not a duplicate of the file, to verify file integrity :) I agree it's a bit...weirdly worded by me :)

                      – vidarlo
                      11 mins ago











                    • OOOOOh. OK, I've read the sentence again. Sorry, my brain foobared there. Yes, hash allows knowing that data is the same without having a duplicate copy of file to compare with to see if it changed.

                      – Sergiy Kolodyazhnyy
                      9 mins ago

















                    "It also allows you to verify that a file has not changed, without having to store the full file." Well, files stored on local hard drive are already ... stored :) But looking at modification time in ls -l or stat output is probably faster than calculating checksum in such case . Nice answer, very concise. Have a +1

                    – Sergiy Kolodyazhnyy
                    17 mins ago





                    "It also allows you to verify that a file has not changed, without having to store the full file." Well, files stored on local hard drive are already ... stored :) But looking at modification time in ls -l or stat output is probably faster than calculating checksum in such case . Nice answer, very concise. Have a +1

                    – Sergiy Kolodyazhnyy
                    17 mins ago













                    It allows you to store a small piece of data, the checksum, and not a duplicate of the file, to verify file integrity :) I agree it's a bit...weirdly worded by me :)

                    – vidarlo
                    11 mins ago





                    It allows you to store a small piece of data, the checksum, and not a duplicate of the file, to verify file integrity :) I agree it's a bit...weirdly worded by me :)

                    – vidarlo
                    11 mins ago













                    OOOOOh. OK, I've read the sentence again. Sorry, my brain foobared there. Yes, hash allows knowing that data is the same without having a duplicate copy of file to compare with to see if it changed.

                    – Sergiy Kolodyazhnyy
                    9 mins ago





                    OOOOOh. OK, I've read the sentence again. Sorry, my brain foobared there. Yes, hash allows knowing that data is the same without having a duplicate copy of file to compare with to see if it changed.

                    – Sergiy Kolodyazhnyy
                    9 mins ago


















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