How to use sed for substituting 2nd column in shell










0















I have file that looks like this :



1,2,3,4
5,6,7,8


I want to substitute 2rd column containing 6 to 89. The desired output is



1,2,3,4
5,89,7,8


But if I type



index=2
cat file | sed 's/[^,]*/89/'$index


I get



1,89,3,4
5,89,7,8


and if I type



index=2
cat file | sed 's/[^,]6/89/'$index


nothing changes.
Why is it like this? How can I fix this? Thank you.










share|improve this question

















  • 1





    [^,] matches a single character which is not comma (or newline). It is unclear what you imagine it should match.

    – tripleee
    Nov 13 '18 at 4:59











  • Possible duplicate of How to replace second column of csv file with a specific value "XYX"

    – tripleee
    Nov 13 '18 at 4:59






  • 1





    Also, the cat is useless.

    – tripleee
    Nov 13 '18 at 5:01






  • 1





    Possible duplicate of stackoverflow.com/questions/49833671/…

    – tripleee
    Nov 13 '18 at 5:05











  • Yes I did not know what [^,] means. Thank you! I don't need to substitute all lines

    – Sumin Kim
    Nov 13 '18 at 6:02















0















I have file that looks like this :



1,2,3,4
5,6,7,8


I want to substitute 2rd column containing 6 to 89. The desired output is



1,2,3,4
5,89,7,8


But if I type



index=2
cat file | sed 's/[^,]*/89/'$index


I get



1,89,3,4
5,89,7,8


and if I type



index=2
cat file | sed 's/[^,]6/89/'$index


nothing changes.
Why is it like this? How can I fix this? Thank you.










share|improve this question

















  • 1





    [^,] matches a single character which is not comma (or newline). It is unclear what you imagine it should match.

    – tripleee
    Nov 13 '18 at 4:59











  • Possible duplicate of How to replace second column of csv file with a specific value "XYX"

    – tripleee
    Nov 13 '18 at 4:59






  • 1





    Also, the cat is useless.

    – tripleee
    Nov 13 '18 at 5:01






  • 1





    Possible duplicate of stackoverflow.com/questions/49833671/…

    – tripleee
    Nov 13 '18 at 5:05











  • Yes I did not know what [^,] means. Thank you! I don't need to substitute all lines

    – Sumin Kim
    Nov 13 '18 at 6:02













0












0








0








I have file that looks like this :



1,2,3,4
5,6,7,8


I want to substitute 2rd column containing 6 to 89. The desired output is



1,2,3,4
5,89,7,8


But if I type



index=2
cat file | sed 's/[^,]*/89/'$index


I get



1,89,3,4
5,89,7,8


and if I type



index=2
cat file | sed 's/[^,]6/89/'$index


nothing changes.
Why is it like this? How can I fix this? Thank you.










share|improve this question














I have file that looks like this :



1,2,3,4
5,6,7,8


I want to substitute 2rd column containing 6 to 89. The desired output is



1,2,3,4
5,89,7,8


But if I type



index=2
cat file | sed 's/[^,]*/89/'$index


I get



1,89,3,4
5,89,7,8


and if I type



index=2
cat file | sed 's/[^,]6/89/'$index


nothing changes.
Why is it like this? How can I fix this? Thank you.







sed






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Nov 13 '18 at 4:55









Sumin KimSumin Kim

1028




1028







  • 1





    [^,] matches a single character which is not comma (or newline). It is unclear what you imagine it should match.

    – tripleee
    Nov 13 '18 at 4:59











  • Possible duplicate of How to replace second column of csv file with a specific value "XYX"

    – tripleee
    Nov 13 '18 at 4:59






  • 1





    Also, the cat is useless.

    – tripleee
    Nov 13 '18 at 5:01






  • 1





    Possible duplicate of stackoverflow.com/questions/49833671/…

    – tripleee
    Nov 13 '18 at 5:05











  • Yes I did not know what [^,] means. Thank you! I don't need to substitute all lines

    – Sumin Kim
    Nov 13 '18 at 6:02












  • 1





    [^,] matches a single character which is not comma (or newline). It is unclear what you imagine it should match.

    – tripleee
    Nov 13 '18 at 4:59











  • Possible duplicate of How to replace second column of csv file with a specific value "XYX"

    – tripleee
    Nov 13 '18 at 4:59






  • 1





    Also, the cat is useless.

    – tripleee
    Nov 13 '18 at 5:01






  • 1





    Possible duplicate of stackoverflow.com/questions/49833671/…

    – tripleee
    Nov 13 '18 at 5:05











  • Yes I did not know what [^,] means. Thank you! I don't need to substitute all lines

    – Sumin Kim
    Nov 13 '18 at 6:02







1




1





[^,] matches a single character which is not comma (or newline). It is unclear what you imagine it should match.

– tripleee
Nov 13 '18 at 4:59





[^,] matches a single character which is not comma (or newline). It is unclear what you imagine it should match.

– tripleee
Nov 13 '18 at 4:59













Possible duplicate of How to replace second column of csv file with a specific value "XYX"

– tripleee
Nov 13 '18 at 4:59





Possible duplicate of How to replace second column of csv file with a specific value "XYX"

– tripleee
Nov 13 '18 at 4:59




1




1





Also, the cat is useless.

– tripleee
Nov 13 '18 at 5:01





Also, the cat is useless.

– tripleee
Nov 13 '18 at 5:01




1




1





Possible duplicate of stackoverflow.com/questions/49833671/…

– tripleee
Nov 13 '18 at 5:05





Possible duplicate of stackoverflow.com/questions/49833671/…

– tripleee
Nov 13 '18 at 5:05













Yes I did not know what [^,] means. Thank you! I don't need to substitute all lines

– Sumin Kim
Nov 13 '18 at 6:02





Yes I did not know what [^,] means. Thank you! I don't need to substitute all lines

– Sumin Kim
Nov 13 '18 at 6:02












2 Answers
2






active

oldest

votes


















2














Since you want to change the second column containing a 6 and you have a comma as field separator it is actually very easy with sed:



sed 's/^([^,]*),6,/1,89,/`


Here we make use of back-referencing to remember the first column.



If you want to replace the 6 in the 5th column, you can do something like:



sed 's/^(([^,]*,)4)6,/189,/'


It is, however, much more comfortable using awk:



awk 'BEGINFS=OFS=","($2==6)$2=891'





share|improve this answer























  • Thank you very much!

    – Sumin Kim
    Nov 14 '18 at 9:36


















0














I solved this by using awk



awk 'BEGINFS=OFS="," if ($2==6) $2=891' file >file1





share|improve this answer






















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    2 Answers
    2






    active

    oldest

    votes








    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    2














    Since you want to change the second column containing a 6 and you have a comma as field separator it is actually very easy with sed:



    sed 's/^([^,]*),6,/1,89,/`


    Here we make use of back-referencing to remember the first column.



    If you want to replace the 6 in the 5th column, you can do something like:



    sed 's/^(([^,]*,)4)6,/189,/'


    It is, however, much more comfortable using awk:



    awk 'BEGINFS=OFS=","($2==6)$2=891'





    share|improve this answer























    • Thank you very much!

      – Sumin Kim
      Nov 14 '18 at 9:36















    2














    Since you want to change the second column containing a 6 and you have a comma as field separator it is actually very easy with sed:



    sed 's/^([^,]*),6,/1,89,/`


    Here we make use of back-referencing to remember the first column.



    If you want to replace the 6 in the 5th column, you can do something like:



    sed 's/^(([^,]*,)4)6,/189,/'


    It is, however, much more comfortable using awk:



    awk 'BEGINFS=OFS=","($2==6)$2=891'





    share|improve this answer























    • Thank you very much!

      – Sumin Kim
      Nov 14 '18 at 9:36













    2












    2








    2







    Since you want to change the second column containing a 6 and you have a comma as field separator it is actually very easy with sed:



    sed 's/^([^,]*),6,/1,89,/`


    Here we make use of back-referencing to remember the first column.



    If you want to replace the 6 in the 5th column, you can do something like:



    sed 's/^(([^,]*,)4)6,/189,/'


    It is, however, much more comfortable using awk:



    awk 'BEGINFS=OFS=","($2==6)$2=891'





    share|improve this answer













    Since you want to change the second column containing a 6 and you have a comma as field separator it is actually very easy with sed:



    sed 's/^([^,]*),6,/1,89,/`


    Here we make use of back-referencing to remember the first column.



    If you want to replace the 6 in the 5th column, you can do something like:



    sed 's/^(([^,]*,)4)6,/189,/'


    It is, however, much more comfortable using awk:



    awk 'BEGINFS=OFS=","($2==6)$2=891'






    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered Nov 13 '18 at 11:37









    kvantourkvantour

    8,62731330




    8,62731330












    • Thank you very much!

      – Sumin Kim
      Nov 14 '18 at 9:36

















    • Thank you very much!

      – Sumin Kim
      Nov 14 '18 at 9:36
















    Thank you very much!

    – Sumin Kim
    Nov 14 '18 at 9:36





    Thank you very much!

    – Sumin Kim
    Nov 14 '18 at 9:36













    0














    I solved this by using awk



    awk 'BEGINFS=OFS="," if ($2==6) $2=891' file >file1





    share|improve this answer



























      0














      I solved this by using awk



      awk 'BEGINFS=OFS="," if ($2==6) $2=891' file >file1





      share|improve this answer

























        0












        0








        0







        I solved this by using awk



        awk 'BEGINFS=OFS="," if ($2==6) $2=891' file >file1





        share|improve this answer













        I solved this by using awk



        awk 'BEGINFS=OFS="," if ($2==6) $2=891' file >file1






        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered Nov 13 '18 at 6:03









        Sumin KimSumin Kim

        1028




        1028



























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