What do the dots in this tr command do: tr …A-Z A-ZA-Z <<< “JVPQBOV” (with 13 dots)what is the benefit of --squeeze-repeats in tr commandWhy can't tr read from /dev/urandom on OSX?broken pipe error with popen and JS ffiIs the historical Unix V5 tr command padding behavior of set2 different from what we consider today “classic” System V (1983-1988) behavior?Heirloom Toolchest tr: error(s) trying to delete the complement of a set containing a multibyte character?how to substitute minus sign with trPulling IP address from ping command with sed?Why does tr -sc 'A-Za-z' '[12*]' includes empty line?I cannot understand what -c parameter does in tr command in Ubuntu GNU/Linux even though I read the manualStrange behaviour of tr using ranges

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What do the dots in this tr command do: tr …A-Z A-ZA-Z


what is the benefit of --squeeze-repeats in tr commandWhy can't tr read from /dev/urandom on OSX?broken pipe error with popen and JS ffiIs the historical Unix V5 tr command padding behavior of set2 different from what we consider today “classic” System V (1983-1988) behavior?Heirloom Toolchest tr: error(s) trying to delete the complement of a set containing a multibyte character?how to substitute minus sign with trPulling IP address from ping command with sed?Why does tr -sc 'A-Za-z' '[12*]' includes empty line?I cannot understand what -c parameter does in tr command in Ubuntu GNU/Linux even though I read the manualStrange behaviour of tr using ranges






.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;








4















I want to use tr to do some rot13 transformation. I can beautifully understand this command:



tr A-Za-z N-ZA-Mn-za-m <<< "URYC ZR CYRNFR"


which output is HELP ME PLEASE, but I can't figure out how this other command can produce the same rot13 transformation:



tr .............A-Z A-ZA-Z <<< "URYC ZR CYRNFR"


So I have two questions:



  1. What's the magic behind the second tr command?

  2. How to make the second command work for both lower and upper case, just like the first command?









share|improve this question









New contributor




Frederico Oliveira is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.




















  • (count the dots)

    – Michael Homer
    1 hour ago











  • I know there's 13 dots. What I wanna know is how it works. There's no explanation about dots in the manual

    – Frederico Oliveira
    1 hour ago






  • 1





    you had better hope you don't run into a dot in your input text

    – iruvar
    1 hour ago

















4















I want to use tr to do some rot13 transformation. I can beautifully understand this command:



tr A-Za-z N-ZA-Mn-za-m <<< "URYC ZR CYRNFR"


which output is HELP ME PLEASE, but I can't figure out how this other command can produce the same rot13 transformation:



tr .............A-Z A-ZA-Z <<< "URYC ZR CYRNFR"


So I have two questions:



  1. What's the magic behind the second tr command?

  2. How to make the second command work for both lower and upper case, just like the first command?









share|improve this question









New contributor




Frederico Oliveira is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.




















  • (count the dots)

    – Michael Homer
    1 hour ago











  • I know there's 13 dots. What I wanna know is how it works. There's no explanation about dots in the manual

    – Frederico Oliveira
    1 hour ago






  • 1





    you had better hope you don't run into a dot in your input text

    – iruvar
    1 hour ago













4












4








4








I want to use tr to do some rot13 transformation. I can beautifully understand this command:



tr A-Za-z N-ZA-Mn-za-m <<< "URYC ZR CYRNFR"


which output is HELP ME PLEASE, but I can't figure out how this other command can produce the same rot13 transformation:



tr .............A-Z A-ZA-Z <<< "URYC ZR CYRNFR"


So I have two questions:



  1. What's the magic behind the second tr command?

  2. How to make the second command work for both lower and upper case, just like the first command?









share|improve this question









New contributor




Frederico Oliveira is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.












I want to use tr to do some rot13 transformation. I can beautifully understand this command:



tr A-Za-z N-ZA-Mn-za-m <<< "URYC ZR CYRNFR"


which output is HELP ME PLEASE, but I can't figure out how this other command can produce the same rot13 transformation:



tr .............A-Z A-ZA-Z <<< "URYC ZR CYRNFR"


So I have two questions:



  1. What's the magic behind the second tr command?

  2. How to make the second command work for both lower and upper case, just like the first command?






tr






share|improve this question









New contributor




Frederico Oliveira is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question









New contributor




Frederico Oliveira is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









share|improve this question




share|improve this question








edited 1 hour ago









Michael Homer

50.6k8140177




50.6k8140177






New contributor




Frederico Oliveira is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









asked 2 hours ago









Frederico OliveiraFrederico Oliveira

212




212




New contributor




Frederico Oliveira is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





New contributor





Frederico Oliveira is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






Frederico Oliveira is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.












  • (count the dots)

    – Michael Homer
    1 hour ago











  • I know there's 13 dots. What I wanna know is how it works. There's no explanation about dots in the manual

    – Frederico Oliveira
    1 hour ago






  • 1





    you had better hope you don't run into a dot in your input text

    – iruvar
    1 hour ago

















  • (count the dots)

    – Michael Homer
    1 hour ago











  • I know there's 13 dots. What I wanna know is how it works. There's no explanation about dots in the manual

    – Frederico Oliveira
    1 hour ago






  • 1





    you had better hope you don't run into a dot in your input text

    – iruvar
    1 hour ago
















(count the dots)

– Michael Homer
1 hour ago





(count the dots)

– Michael Homer
1 hour ago













I know there's 13 dots. What I wanna know is how it works. There's no explanation about dots in the manual

– Frederico Oliveira
1 hour ago





I know there's 13 dots. What I wanna know is how it works. There's no explanation about dots in the manual

– Frederico Oliveira
1 hour ago




1




1





you had better hope you don't run into a dot in your input text

– iruvar
1 hour ago





you had better hope you don't run into a dot in your input text

– iruvar
1 hour ago










2 Answers
2






active

oldest

votes


















2














It works as follows:



SET1-> .............ABCDEFGHIJKLMNOPQRSTUVWXYZ
SET2-> ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLM


So tr will translate SET1 to SET2.



This is equivalent to first one because it is also shifting by 13 units as there 13 dots.






share|improve this answer






























    0














    Ok, so thanks to @Prvt_Yadv I was able to understand the dots. Here's the first question answer:




    What's the magic behind the second tr command?




    The dots are replaced by a sequence of letters starting from a to the number of dots. So



    tr .............A-Z A-ZA-Z will translate to tr A-MA-Z A-ZA-Z



    In this case the sets are:



    SET1 -> ABCDEFGHIJKLMABCDEFGHIJKLMNOPQRSTUVXWYZ
    SET2 -> ABCDEFGHIJKLMNOPQRSTUVXWYZABCDEFGHIJKLMNOPQRSTUVXWYZ


    But since the beginning of both sets are identical until letter M, this part is discarded becoming then



    SET1 -> ABCDEFGHIJKLMNOPQRSTUVXWYZ
    SET2 -> NOPQRSTUVXWYZABCDEFGHIJKLMNOPQRSTUVXWYZ


    But since the first set already contains all 26 letters and set2 has repeating trailing letter, those are discarded too, finally becoming



    SET1 -> ABCDEFGHIJKLMNOPQRSTUVXWYZ
    SET2 -> NOPQRSTUVXWYZABCDEFGHIJKLM


    Which is the rot13 substitution and identical to the first command (except for not dealing with lower cases here). The same logic can be applied for the title of the question:



    tr ...A-Z A-ZA-Z <<< “JVPQBOV” would become tr A-CA-Z A-ZA-Z <<< “JVPQBOV”



    The sets being:



    SET1 -> ABCABCDEFGHIJKLMNOPQRSTUVXWYZ
    SET2 -> ABCDEFGHIJKLMNOPQRSTUVXWYZABCDEFGHIJKLMNOPQRSTUVXWYZ


    Discarding the initial identical sequence and the trailing repeating letters they become:



    SET1 -> ABCDEFGHIJKLMNOPQRSTUVXWYZ
    SET2 -> DEFGHIJKLMNOPQRSTUVXWYZABC


    Which is the rot3 substitution.



    Now for the second question:




    How to make the second command work for both lower and upper case, just like the first command?




    The dots are substituted by a sequence of letter of the same case as the next sequence. That means that tr .....A-Z will translate to tr A-EA-Z whereas tr .....a-z will translate to tr a-ea-z. But the dots only work before the literal sequence, not after. So the immediate solution idea tr .....A-Z.....a-z won't work, because it will not translate to tr A-EA-Za-ea-z. The only reliable way to make it work is to use two tr commands as follow



    tr .............A-Z A-ZA-Z <<< "ABJ V hqrefgnaq" | tr .............a-z a-za-z


    Now it works for both upper and lower case :)



    A caveat to using the dots substitution was gave by @iruvar: this command will not work as expected when the input stings has dots. So the following command won't print T.h.a.n.k.s.



    tr .............A-Z A-ZA-Z <<< "G.u.n.a.x.f." | tr .............a-z a-za-z


    It will print TMhMaMnMkMsM instead, substituting the dots to M






    share|improve this answer










    New contributor




    Frederico Oliveira is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.




















      Your Answer








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      2 Answers
      2






      active

      oldest

      votes








      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      2














      It works as follows:



      SET1-> .............ABCDEFGHIJKLMNOPQRSTUVWXYZ
      SET2-> ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLM


      So tr will translate SET1 to SET2.



      This is equivalent to first one because it is also shifting by 13 units as there 13 dots.






      share|improve this answer



























        2














        It works as follows:



        SET1-> .............ABCDEFGHIJKLMNOPQRSTUVWXYZ
        SET2-> ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLM


        So tr will translate SET1 to SET2.



        This is equivalent to first one because it is also shifting by 13 units as there 13 dots.






        share|improve this answer

























          2












          2








          2







          It works as follows:



          SET1-> .............ABCDEFGHIJKLMNOPQRSTUVWXYZ
          SET2-> ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLM


          So tr will translate SET1 to SET2.



          This is equivalent to first one because it is also shifting by 13 units as there 13 dots.






          share|improve this answer













          It works as follows:



          SET1-> .............ABCDEFGHIJKLMNOPQRSTUVWXYZ
          SET2-> ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLM


          So tr will translate SET1 to SET2.



          This is equivalent to first one because it is also shifting by 13 units as there 13 dots.







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered 1 hour ago









          Prvt_YadvPrvt_Yadv

          3,07631329




          3,07631329























              0














              Ok, so thanks to @Prvt_Yadv I was able to understand the dots. Here's the first question answer:




              What's the magic behind the second tr command?




              The dots are replaced by a sequence of letters starting from a to the number of dots. So



              tr .............A-Z A-ZA-Z will translate to tr A-MA-Z A-ZA-Z



              In this case the sets are:



              SET1 -> ABCDEFGHIJKLMABCDEFGHIJKLMNOPQRSTUVXWYZ
              SET2 -> ABCDEFGHIJKLMNOPQRSTUVXWYZABCDEFGHIJKLMNOPQRSTUVXWYZ


              But since the beginning of both sets are identical until letter M, this part is discarded becoming then



              SET1 -> ABCDEFGHIJKLMNOPQRSTUVXWYZ
              SET2 -> NOPQRSTUVXWYZABCDEFGHIJKLMNOPQRSTUVXWYZ


              But since the first set already contains all 26 letters and set2 has repeating trailing letter, those are discarded too, finally becoming



              SET1 -> ABCDEFGHIJKLMNOPQRSTUVXWYZ
              SET2 -> NOPQRSTUVXWYZABCDEFGHIJKLM


              Which is the rot13 substitution and identical to the first command (except for not dealing with lower cases here). The same logic can be applied for the title of the question:



              tr ...A-Z A-ZA-Z <<< “JVPQBOV” would become tr A-CA-Z A-ZA-Z <<< “JVPQBOV”



              The sets being:



              SET1 -> ABCABCDEFGHIJKLMNOPQRSTUVXWYZ
              SET2 -> ABCDEFGHIJKLMNOPQRSTUVXWYZABCDEFGHIJKLMNOPQRSTUVXWYZ


              Discarding the initial identical sequence and the trailing repeating letters they become:



              SET1 -> ABCDEFGHIJKLMNOPQRSTUVXWYZ
              SET2 -> DEFGHIJKLMNOPQRSTUVXWYZABC


              Which is the rot3 substitution.



              Now for the second question:




              How to make the second command work for both lower and upper case, just like the first command?




              The dots are substituted by a sequence of letter of the same case as the next sequence. That means that tr .....A-Z will translate to tr A-EA-Z whereas tr .....a-z will translate to tr a-ea-z. But the dots only work before the literal sequence, not after. So the immediate solution idea tr .....A-Z.....a-z won't work, because it will not translate to tr A-EA-Za-ea-z. The only reliable way to make it work is to use two tr commands as follow



              tr .............A-Z A-ZA-Z <<< "ABJ V hqrefgnaq" | tr .............a-z a-za-z


              Now it works for both upper and lower case :)



              A caveat to using the dots substitution was gave by @iruvar: this command will not work as expected when the input stings has dots. So the following command won't print T.h.a.n.k.s.



              tr .............A-Z A-ZA-Z <<< "G.u.n.a.x.f." | tr .............a-z a-za-z


              It will print TMhMaMnMkMsM instead, substituting the dots to M






              share|improve this answer










              New contributor




              Frederico Oliveira is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
              Check out our Code of Conduct.
























                0














                Ok, so thanks to @Prvt_Yadv I was able to understand the dots. Here's the first question answer:




                What's the magic behind the second tr command?




                The dots are replaced by a sequence of letters starting from a to the number of dots. So



                tr .............A-Z A-ZA-Z will translate to tr A-MA-Z A-ZA-Z



                In this case the sets are:



                SET1 -> ABCDEFGHIJKLMABCDEFGHIJKLMNOPQRSTUVXWYZ
                SET2 -> ABCDEFGHIJKLMNOPQRSTUVXWYZABCDEFGHIJKLMNOPQRSTUVXWYZ


                But since the beginning of both sets are identical until letter M, this part is discarded becoming then



                SET1 -> ABCDEFGHIJKLMNOPQRSTUVXWYZ
                SET2 -> NOPQRSTUVXWYZABCDEFGHIJKLMNOPQRSTUVXWYZ


                But since the first set already contains all 26 letters and set2 has repeating trailing letter, those are discarded too, finally becoming



                SET1 -> ABCDEFGHIJKLMNOPQRSTUVXWYZ
                SET2 -> NOPQRSTUVXWYZABCDEFGHIJKLM


                Which is the rot13 substitution and identical to the first command (except for not dealing with lower cases here). The same logic can be applied for the title of the question:



                tr ...A-Z A-ZA-Z <<< “JVPQBOV” would become tr A-CA-Z A-ZA-Z <<< “JVPQBOV”



                The sets being:



                SET1 -> ABCABCDEFGHIJKLMNOPQRSTUVXWYZ
                SET2 -> ABCDEFGHIJKLMNOPQRSTUVXWYZABCDEFGHIJKLMNOPQRSTUVXWYZ


                Discarding the initial identical sequence and the trailing repeating letters they become:



                SET1 -> ABCDEFGHIJKLMNOPQRSTUVXWYZ
                SET2 -> DEFGHIJKLMNOPQRSTUVXWYZABC


                Which is the rot3 substitution.



                Now for the second question:




                How to make the second command work for both lower and upper case, just like the first command?




                The dots are substituted by a sequence of letter of the same case as the next sequence. That means that tr .....A-Z will translate to tr A-EA-Z whereas tr .....a-z will translate to tr a-ea-z. But the dots only work before the literal sequence, not after. So the immediate solution idea tr .....A-Z.....a-z won't work, because it will not translate to tr A-EA-Za-ea-z. The only reliable way to make it work is to use two tr commands as follow



                tr .............A-Z A-ZA-Z <<< "ABJ V hqrefgnaq" | tr .............a-z a-za-z


                Now it works for both upper and lower case :)



                A caveat to using the dots substitution was gave by @iruvar: this command will not work as expected when the input stings has dots. So the following command won't print T.h.a.n.k.s.



                tr .............A-Z A-ZA-Z <<< "G.u.n.a.x.f." | tr .............a-z a-za-z


                It will print TMhMaMnMkMsM instead, substituting the dots to M






                share|improve this answer










                New contributor




                Frederico Oliveira is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.






















                  0












                  0








                  0







                  Ok, so thanks to @Prvt_Yadv I was able to understand the dots. Here's the first question answer:




                  What's the magic behind the second tr command?




                  The dots are replaced by a sequence of letters starting from a to the number of dots. So



                  tr .............A-Z A-ZA-Z will translate to tr A-MA-Z A-ZA-Z



                  In this case the sets are:



                  SET1 -> ABCDEFGHIJKLMABCDEFGHIJKLMNOPQRSTUVXWYZ
                  SET2 -> ABCDEFGHIJKLMNOPQRSTUVXWYZABCDEFGHIJKLMNOPQRSTUVXWYZ


                  But since the beginning of both sets are identical until letter M, this part is discarded becoming then



                  SET1 -> ABCDEFGHIJKLMNOPQRSTUVXWYZ
                  SET2 -> NOPQRSTUVXWYZABCDEFGHIJKLMNOPQRSTUVXWYZ


                  But since the first set already contains all 26 letters and set2 has repeating trailing letter, those are discarded too, finally becoming



                  SET1 -> ABCDEFGHIJKLMNOPQRSTUVXWYZ
                  SET2 -> NOPQRSTUVXWYZABCDEFGHIJKLM


                  Which is the rot13 substitution and identical to the first command (except for not dealing with lower cases here). The same logic can be applied for the title of the question:



                  tr ...A-Z A-ZA-Z <<< “JVPQBOV” would become tr A-CA-Z A-ZA-Z <<< “JVPQBOV”



                  The sets being:



                  SET1 -> ABCABCDEFGHIJKLMNOPQRSTUVXWYZ
                  SET2 -> ABCDEFGHIJKLMNOPQRSTUVXWYZABCDEFGHIJKLMNOPQRSTUVXWYZ


                  Discarding the initial identical sequence and the trailing repeating letters they become:



                  SET1 -> ABCDEFGHIJKLMNOPQRSTUVXWYZ
                  SET2 -> DEFGHIJKLMNOPQRSTUVXWYZABC


                  Which is the rot3 substitution.



                  Now for the second question:




                  How to make the second command work for both lower and upper case, just like the first command?




                  The dots are substituted by a sequence of letter of the same case as the next sequence. That means that tr .....A-Z will translate to tr A-EA-Z whereas tr .....a-z will translate to tr a-ea-z. But the dots only work before the literal sequence, not after. So the immediate solution idea tr .....A-Z.....a-z won't work, because it will not translate to tr A-EA-Za-ea-z. The only reliable way to make it work is to use two tr commands as follow



                  tr .............A-Z A-ZA-Z <<< "ABJ V hqrefgnaq" | tr .............a-z a-za-z


                  Now it works for both upper and lower case :)



                  A caveat to using the dots substitution was gave by @iruvar: this command will not work as expected when the input stings has dots. So the following command won't print T.h.a.n.k.s.



                  tr .............A-Z A-ZA-Z <<< "G.u.n.a.x.f." | tr .............a-z a-za-z


                  It will print TMhMaMnMkMsM instead, substituting the dots to M






                  share|improve this answer










                  New contributor




                  Frederico Oliveira is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                  Check out our Code of Conduct.










                  Ok, so thanks to @Prvt_Yadv I was able to understand the dots. Here's the first question answer:




                  What's the magic behind the second tr command?




                  The dots are replaced by a sequence of letters starting from a to the number of dots. So



                  tr .............A-Z A-ZA-Z will translate to tr A-MA-Z A-ZA-Z



                  In this case the sets are:



                  SET1 -> ABCDEFGHIJKLMABCDEFGHIJKLMNOPQRSTUVXWYZ
                  SET2 -> ABCDEFGHIJKLMNOPQRSTUVXWYZABCDEFGHIJKLMNOPQRSTUVXWYZ


                  But since the beginning of both sets are identical until letter M, this part is discarded becoming then



                  SET1 -> ABCDEFGHIJKLMNOPQRSTUVXWYZ
                  SET2 -> NOPQRSTUVXWYZABCDEFGHIJKLMNOPQRSTUVXWYZ


                  But since the first set already contains all 26 letters and set2 has repeating trailing letter, those are discarded too, finally becoming



                  SET1 -> ABCDEFGHIJKLMNOPQRSTUVXWYZ
                  SET2 -> NOPQRSTUVXWYZABCDEFGHIJKLM


                  Which is the rot13 substitution and identical to the first command (except for not dealing with lower cases here). The same logic can be applied for the title of the question:



                  tr ...A-Z A-ZA-Z <<< “JVPQBOV” would become tr A-CA-Z A-ZA-Z <<< “JVPQBOV”



                  The sets being:



                  SET1 -> ABCABCDEFGHIJKLMNOPQRSTUVXWYZ
                  SET2 -> ABCDEFGHIJKLMNOPQRSTUVXWYZABCDEFGHIJKLMNOPQRSTUVXWYZ


                  Discarding the initial identical sequence and the trailing repeating letters they become:



                  SET1 -> ABCDEFGHIJKLMNOPQRSTUVXWYZ
                  SET2 -> DEFGHIJKLMNOPQRSTUVXWYZABC


                  Which is the rot3 substitution.



                  Now for the second question:




                  How to make the second command work for both lower and upper case, just like the first command?




                  The dots are substituted by a sequence of letter of the same case as the next sequence. That means that tr .....A-Z will translate to tr A-EA-Z whereas tr .....a-z will translate to tr a-ea-z. But the dots only work before the literal sequence, not after. So the immediate solution idea tr .....A-Z.....a-z won't work, because it will not translate to tr A-EA-Za-ea-z. The only reliable way to make it work is to use two tr commands as follow



                  tr .............A-Z A-ZA-Z <<< "ABJ V hqrefgnaq" | tr .............a-z a-za-z


                  Now it works for both upper and lower case :)



                  A caveat to using the dots substitution was gave by @iruvar: this command will not work as expected when the input stings has dots. So the following command won't print T.h.a.n.k.s.



                  tr .............A-Z A-ZA-Z <<< "G.u.n.a.x.f." | tr .............a-z a-za-z


                  It will print TMhMaMnMkMsM instead, substituting the dots to M







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                  answered 27 mins ago









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