Does cd . have use?












1















One of the tutorials I've been following briefly stated that cd . has no use. When trying to replicate issue shown by OP in Symbolic link recursion - what makes it “reset”?, I also tried cd ., which showed the same effect OP described (growing $PWD variable), which can be countered with cd -P.



This makes me wonder, is there any case where one does in fact would want to use cd . ?






cd-command







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    1















    One of the tutorials I've been following briefly stated that cd . has no use. When trying to replicate issue shown by OP in Symbolic link recursion - what makes it “reset”?, I also tried cd ., which showed the same effect OP described (growing $PWD variable), which can be countered with cd -P.



    This makes me wonder, is there any case where one does in fact would want to use cd . ?






    cd-command







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      1








      1








      One of the tutorials I've been following briefly stated that cd . has no use. When trying to replicate issue shown by OP in Symbolic link recursion - what makes it “reset”?, I also tried cd ., which showed the same effect OP described (growing $PWD variable), which can be countered with cd -P.



      This makes me wonder, is there any case where one does in fact would want to use cd . ?






      cd-command







      share|improve this question














      One of the tutorials I've been following briefly stated that cd . has no use. When trying to replicate issue shown by OP in Symbolic link recursion - what makes it “reset”?, I also tried cd ., which showed the same effect OP described (growing $PWD variable), which can be countered with cd -P.



      This makes me wonder, is there any case where one does in fact would want to use cd . ?






      cd-command




      cd-command






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      asked 11 mins ago









      Sergiy KolodyazhnyySergiy Kolodyazhnyy

      8,69412355




      8,69412355






















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          The path of directory could have changed since the last executed command and without cd . bash and ksh93 shells will rely on logical working directory described in the linked post in the question; so calling cd . which makes the shell issue getcwd() syscall, will ensure your current path is still valid.



          Steps to reproduce in bash:




          1. in terminal tab issue mkdir ./dir_no_1; cd ./dir_no_1

          2. in different terminal tab issue mv dir_no_1 dir_no_2

          3. issue in first terminal tab echo $PWD and pwd. Notice that the directory has been externally renamed, shell's environment has not been updated.

          4. issue cd .; pwd; echo $PWD. Notice the value will be updated.


          ksh93, however, does not update the environment information, so cd . in ksh93 may in fact be useless. In /bin/dash on Ubuntu and other Debian based systems, cd . returns dash: 3: cd: can't cd to . error, however cd -P . works ( unlike in ksh93 ).






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            The path of directory could have changed since the last executed command and without cd . bash and ksh93 shells will rely on logical working directory described in the linked post in the question; so calling cd . which makes the shell issue getcwd() syscall, will ensure your current path is still valid.



            Steps to reproduce in bash:




            1. in terminal tab issue mkdir ./dir_no_1; cd ./dir_no_1

            2. in different terminal tab issue mv dir_no_1 dir_no_2

            3. issue in first terminal tab echo $PWD and pwd. Notice that the directory has been externally renamed, shell's environment has not been updated.

            4. issue cd .; pwd; echo $PWD. Notice the value will be updated.


            ksh93, however, does not update the environment information, so cd . in ksh93 may in fact be useless. In /bin/dash on Ubuntu and other Debian based systems, cd . returns dash: 3: cd: can't cd to . error, however cd -P . works ( unlike in ksh93 ).






            share|improve this answer




























              1














              The path of directory could have changed since the last executed command and without cd . bash and ksh93 shells will rely on logical working directory described in the linked post in the question; so calling cd . which makes the shell issue getcwd() syscall, will ensure your current path is still valid.



              Steps to reproduce in bash:




              1. in terminal tab issue mkdir ./dir_no_1; cd ./dir_no_1

              2. in different terminal tab issue mv dir_no_1 dir_no_2

              3. issue in first terminal tab echo $PWD and pwd. Notice that the directory has been externally renamed, shell's environment has not been updated.

              4. issue cd .; pwd; echo $PWD. Notice the value will be updated.


              ksh93, however, does not update the environment information, so cd . in ksh93 may in fact be useless. In /bin/dash on Ubuntu and other Debian based systems, cd . returns dash: 3: cd: can't cd to . error, however cd -P . works ( unlike in ksh93 ).






              share|improve this answer


























                1












                1








                1







                The path of directory could have changed since the last executed command and without cd . bash and ksh93 shells will rely on logical working directory described in the linked post in the question; so calling cd . which makes the shell issue getcwd() syscall, will ensure your current path is still valid.



                Steps to reproduce in bash:




                1. in terminal tab issue mkdir ./dir_no_1; cd ./dir_no_1

                2. in different terminal tab issue mv dir_no_1 dir_no_2

                3. issue in first terminal tab echo $PWD and pwd. Notice that the directory has been externally renamed, shell's environment has not been updated.

                4. issue cd .; pwd; echo $PWD. Notice the value will be updated.


                ksh93, however, does not update the environment information, so cd . in ksh93 may in fact be useless. In /bin/dash on Ubuntu and other Debian based systems, cd . returns dash: 3: cd: can't cd to . error, however cd -P . works ( unlike in ksh93 ).






                share|improve this answer













                The path of directory could have changed since the last executed command and without cd . bash and ksh93 shells will rely on logical working directory described in the linked post in the question; so calling cd . which makes the shell issue getcwd() syscall, will ensure your current path is still valid.



                Steps to reproduce in bash:




                1. in terminal tab issue mkdir ./dir_no_1; cd ./dir_no_1

                2. in different terminal tab issue mv dir_no_1 dir_no_2

                3. issue in first terminal tab echo $PWD and pwd. Notice that the directory has been externally renamed, shell's environment has not been updated.

                4. issue cd .; pwd; echo $PWD. Notice the value will be updated.


                ksh93, however, does not update the environment information, so cd . in ksh93 may in fact be useless. In /bin/dash on Ubuntu and other Debian based systems, cd . returns dash: 3: cd: can't cd to . error, however cd -P . works ( unlike in ksh93 ).







                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered 11 mins ago









                Sergiy KolodyazhnyySergiy Kolodyazhnyy

                8,69412355




                8,69412355






























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