grep : find bigger string in small string

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I am writing a small shell script to receive an input and match against a text file.



However, the input would be a bigger string than the string in the file, against which I want a match.



User input:



abc-de-ef-gh1


Text in file:



This is test,-de-ef-gh,This is test


I want a positive result if I grep user-input with existing file.



How can I achieve this? I couldn't do it with grep.










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  • 2




    how about echo "user input" | grep -f pattern_file
    – Kamaraj
    Aug 31 at 9:09










  • Kamaraj - it doesn't work.
    – Novice
    Aug 31 at 9:15






  • 1




    If the user input and the pattern are as in the question, then the comment of @Kamaraj will work. So your problem is not reproducible. Please give exact input and patterns. "It doesn't work" will not help us to help you.
    – chaos
    Aug 31 at 9:37










  • Apologies as I was unclear. Edited the question.
    – Novice
    Aug 31 at 9:54






  • 1




    This question is unclear. I sort-of understand it, but not clearly enough for it to be answerable.  @Novice: Do you want to match a line that contains abc-d-ef-gh1? How about f-gh? How about -gh1? How about gh or 1?  Describe the processes by which you would answer those questions; i.e., describe the rules that determine whether a string should match a line. Please do not respond in comments; edit your question to make it clearer and more complete.
    – G-Man
    Sep 2 at 20:59














up vote
1
down vote

favorite












I am writing a small shell script to receive an input and match against a text file.



However, the input would be a bigger string than the string in the file, against which I want a match.



User input:



abc-de-ef-gh1


Text in file:



This is test,-de-ef-gh,This is test


I want a positive result if I grep user-input with existing file.



How can I achieve this? I couldn't do it with grep.










share|improve this question



















  • 2




    how about echo "user input" | grep -f pattern_file
    – Kamaraj
    Aug 31 at 9:09










  • Kamaraj - it doesn't work.
    – Novice
    Aug 31 at 9:15






  • 1




    If the user input and the pattern are as in the question, then the comment of @Kamaraj will work. So your problem is not reproducible. Please give exact input and patterns. "It doesn't work" will not help us to help you.
    – chaos
    Aug 31 at 9:37










  • Apologies as I was unclear. Edited the question.
    – Novice
    Aug 31 at 9:54






  • 1




    This question is unclear. I sort-of understand it, but not clearly enough for it to be answerable.  @Novice: Do you want to match a line that contains abc-d-ef-gh1? How about f-gh? How about -gh1? How about gh or 1?  Describe the processes by which you would answer those questions; i.e., describe the rules that determine whether a string should match a line. Please do not respond in comments; edit your question to make it clearer and more complete.
    – G-Man
    Sep 2 at 20:59












up vote
1
down vote

favorite









up vote
1
down vote

favorite











I am writing a small shell script to receive an input and match against a text file.



However, the input would be a bigger string than the string in the file, against which I want a match.



User input:



abc-de-ef-gh1


Text in file:



This is test,-de-ef-gh,This is test


I want a positive result if I grep user-input with existing file.



How can I achieve this? I couldn't do it with grep.










share|improve this question















I am writing a small shell script to receive an input and match against a text file.



However, the input would be a bigger string than the string in the file, against which I want a match.



User input:



abc-de-ef-gh1


Text in file:



This is test,-de-ef-gh,This is test


I want a positive result if I grep user-input with existing file.



How can I achieve this? I couldn't do it with grep.







linux shell grep regular-expression






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share|improve this question













share|improve this question




share|improve this question








edited Aug 31 at 9:51

























asked Aug 31 at 9:07









Novice

92




92







  • 2




    how about echo "user input" | grep -f pattern_file
    – Kamaraj
    Aug 31 at 9:09










  • Kamaraj - it doesn't work.
    – Novice
    Aug 31 at 9:15






  • 1




    If the user input and the pattern are as in the question, then the comment of @Kamaraj will work. So your problem is not reproducible. Please give exact input and patterns. "It doesn't work" will not help us to help you.
    – chaos
    Aug 31 at 9:37










  • Apologies as I was unclear. Edited the question.
    – Novice
    Aug 31 at 9:54






  • 1




    This question is unclear. I sort-of understand it, but not clearly enough for it to be answerable.  @Novice: Do you want to match a line that contains abc-d-ef-gh1? How about f-gh? How about -gh1? How about gh or 1?  Describe the processes by which you would answer those questions; i.e., describe the rules that determine whether a string should match a line. Please do not respond in comments; edit your question to make it clearer and more complete.
    – G-Man
    Sep 2 at 20:59












  • 2




    how about echo "user input" | grep -f pattern_file
    – Kamaraj
    Aug 31 at 9:09










  • Kamaraj - it doesn't work.
    – Novice
    Aug 31 at 9:15






  • 1




    If the user input and the pattern are as in the question, then the comment of @Kamaraj will work. So your problem is not reproducible. Please give exact input and patterns. "It doesn't work" will not help us to help you.
    – chaos
    Aug 31 at 9:37










  • Apologies as I was unclear. Edited the question.
    – Novice
    Aug 31 at 9:54






  • 1




    This question is unclear. I sort-of understand it, but not clearly enough for it to be answerable.  @Novice: Do you want to match a line that contains abc-d-ef-gh1? How about f-gh? How about -gh1? How about gh or 1?  Describe the processes by which you would answer those questions; i.e., describe the rules that determine whether a string should match a line. Please do not respond in comments; edit your question to make it clearer and more complete.
    – G-Man
    Sep 2 at 20:59







2




2




how about echo "user input" | grep -f pattern_file
– Kamaraj
Aug 31 at 9:09




how about echo "user input" | grep -f pattern_file
– Kamaraj
Aug 31 at 9:09












Kamaraj - it doesn't work.
– Novice
Aug 31 at 9:15




Kamaraj - it doesn't work.
– Novice
Aug 31 at 9:15




1




1




If the user input and the pattern are as in the question, then the comment of @Kamaraj will work. So your problem is not reproducible. Please give exact input and patterns. "It doesn't work" will not help us to help you.
– chaos
Aug 31 at 9:37




If the user input and the pattern are as in the question, then the comment of @Kamaraj will work. So your problem is not reproducible. Please give exact input and patterns. "It doesn't work" will not help us to help you.
– chaos
Aug 31 at 9:37












Apologies as I was unclear. Edited the question.
– Novice
Aug 31 at 9:54




Apologies as I was unclear. Edited the question.
– Novice
Aug 31 at 9:54




1




1




This question is unclear. I sort-of understand it, but not clearly enough for it to be answerable.  @Novice: Do you want to match a line that contains abc-d-ef-gh1? How about f-gh? How about -gh1? How about gh or 1?  Describe the processes by which you would answer those questions; i.e., describe the rules that determine whether a string should match a line. Please do not respond in comments; edit your question to make it clearer and more complete.
– G-Man
Sep 2 at 20:59




This question is unclear. I sort-of understand it, but not clearly enough for it to be answerable.  @Novice: Do you want to match a line that contains abc-d-ef-gh1? How about f-gh? How about -gh1? How about gh or 1?  Describe the processes by which you would answer those questions; i.e., describe the rules that determine whether a string should match a line. Please do not respond in comments; edit your question to make it clearer and more complete.
– G-Man
Sep 2 at 20:59










2 Answers
2






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up vote
1
down vote













You have a file with patterns. grep can read the patterns with its -f option. If you want to check whether a string, $input, matches a pattern in patterns.txt, you may do



printf '%sn' "$input" |
if grep -q -f patterns.txt; then
echo 'matches'
else
echo 'does not match'
fi


This would run grep over the contents of the string with the patterns in patterns.txt. In bash you could instead use a here-string:



if grep -q -f patterns.txt <<<"$input"; then
echo 'matches'
else
echo 'does not match'
fi


The -q stops grep from producing output (we're only interested in the exit status).



If the patterns are fixed strings (not regular expressions), use -F with grep in addition to the other flags (grep -qF -f ...).






share|improve this answer



























    up vote
    0
    down vote













    Using bash, cut and grep:



    read -p "Hey user, input something: " $n
    printf "Match "
    grep -m 1 -q -f <(cut -d, -f2 file) <<< "$n" || printf "not "
    printf "found.n"


    Notes:



    • It's impossible to search for a longer string in a shorter, but this is really about finding whether shorter strings in file match a longer string.


    • cut is used to extract the middle field from file


    • grep searches for that middle field in the user input string.


    • printf provides some feedback.





    share|improve this answer




















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      2 Answers
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      up vote
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      down vote













      You have a file with patterns. grep can read the patterns with its -f option. If you want to check whether a string, $input, matches a pattern in patterns.txt, you may do



      printf '%sn' "$input" |
      if grep -q -f patterns.txt; then
      echo 'matches'
      else
      echo 'does not match'
      fi


      This would run grep over the contents of the string with the patterns in patterns.txt. In bash you could instead use a here-string:



      if grep -q -f patterns.txt <<<"$input"; then
      echo 'matches'
      else
      echo 'does not match'
      fi


      The -q stops grep from producing output (we're only interested in the exit status).



      If the patterns are fixed strings (not regular expressions), use -F with grep in addition to the other flags (grep -qF -f ...).






      share|improve this answer
























        up vote
        1
        down vote













        You have a file with patterns. grep can read the patterns with its -f option. If you want to check whether a string, $input, matches a pattern in patterns.txt, you may do



        printf '%sn' "$input" |
        if grep -q -f patterns.txt; then
        echo 'matches'
        else
        echo 'does not match'
        fi


        This would run grep over the contents of the string with the patterns in patterns.txt. In bash you could instead use a here-string:



        if grep -q -f patterns.txt <<<"$input"; then
        echo 'matches'
        else
        echo 'does not match'
        fi


        The -q stops grep from producing output (we're only interested in the exit status).



        If the patterns are fixed strings (not regular expressions), use -F with grep in addition to the other flags (grep -qF -f ...).






        share|improve this answer






















          up vote
          1
          down vote










          up vote
          1
          down vote









          You have a file with patterns. grep can read the patterns with its -f option. If you want to check whether a string, $input, matches a pattern in patterns.txt, you may do



          printf '%sn' "$input" |
          if grep -q -f patterns.txt; then
          echo 'matches'
          else
          echo 'does not match'
          fi


          This would run grep over the contents of the string with the patterns in patterns.txt. In bash you could instead use a here-string:



          if grep -q -f patterns.txt <<<"$input"; then
          echo 'matches'
          else
          echo 'does not match'
          fi


          The -q stops grep from producing output (we're only interested in the exit status).



          If the patterns are fixed strings (not regular expressions), use -F with grep in addition to the other flags (grep -qF -f ...).






          share|improve this answer












          You have a file with patterns. grep can read the patterns with its -f option. If you want to check whether a string, $input, matches a pattern in patterns.txt, you may do



          printf '%sn' "$input" |
          if grep -q -f patterns.txt; then
          echo 'matches'
          else
          echo 'does not match'
          fi


          This would run grep over the contents of the string with the patterns in patterns.txt. In bash you could instead use a here-string:



          if grep -q -f patterns.txt <<<"$input"; then
          echo 'matches'
          else
          echo 'does not match'
          fi


          The -q stops grep from producing output (we're only interested in the exit status).



          If the patterns are fixed strings (not regular expressions), use -F with grep in addition to the other flags (grep -qF -f ...).







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Aug 31 at 9:37









          Kusalananda

          107k14209331




          107k14209331






















              up vote
              0
              down vote













              Using bash, cut and grep:



              read -p "Hey user, input something: " $n
              printf "Match "
              grep -m 1 -q -f <(cut -d, -f2 file) <<< "$n" || printf "not "
              printf "found.n"


              Notes:



              • It's impossible to search for a longer string in a shorter, but this is really about finding whether shorter strings in file match a longer string.


              • cut is used to extract the middle field from file


              • grep searches for that middle field in the user input string.


              • printf provides some feedback.





              share|improve this answer
























                up vote
                0
                down vote













                Using bash, cut and grep:



                read -p "Hey user, input something: " $n
                printf "Match "
                grep -m 1 -q -f <(cut -d, -f2 file) <<< "$n" || printf "not "
                printf "found.n"


                Notes:



                • It's impossible to search for a longer string in a shorter, but this is really about finding whether shorter strings in file match a longer string.


                • cut is used to extract the middle field from file


                • grep searches for that middle field in the user input string.


                • printf provides some feedback.





                share|improve this answer






















                  up vote
                  0
                  down vote










                  up vote
                  0
                  down vote









                  Using bash, cut and grep:



                  read -p "Hey user, input something: " $n
                  printf "Match "
                  grep -m 1 -q -f <(cut -d, -f2 file) <<< "$n" || printf "not "
                  printf "found.n"


                  Notes:



                  • It's impossible to search for a longer string in a shorter, but this is really about finding whether shorter strings in file match a longer string.


                  • cut is used to extract the middle field from file


                  • grep searches for that middle field in the user input string.


                  • printf provides some feedback.





                  share|improve this answer












                  Using bash, cut and grep:



                  read -p "Hey user, input something: " $n
                  printf "Match "
                  grep -m 1 -q -f <(cut -d, -f2 file) <<< "$n" || printf "not "
                  printf "found.n"


                  Notes:



                  • It's impossible to search for a longer string in a shorter, but this is really about finding whether shorter strings in file match a longer string.


                  • cut is used to extract the middle field from file


                  • grep searches for that middle field in the user input string.


                  • printf provides some feedback.






                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered Sep 2 at 5:27









                  agc

                  4,2651935




                  4,2651935



























                       

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