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find string in line

This is a discussion on find string in line within the Linux Programming forums, part of the Platform Specific Boards category; hi all! I'm writing a bash script and I want to find how many times a specific string appears in ...

  1. #1
    quo
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    find string in line

    hi all!

    I'm writing a bash script and I want to find how many times a specific string appears in every line of a file.
    The string I'm looking for is <grow
    The string might be a substring of another string such as:
    old#<grown or young><growup
    Is there a way to achieve that?

  2. #2
    and the hat of int overfl Salem's Avatar
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    Something suitably cryptic...
    $ perl -n -e '$n = ( $_ =~ s/grow//g );print "$n\n";'
    old#<grown or young><growup
    2
    grow grow grow
    3
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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  3. #3
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    Probably less bullet proof than Salem's, but less cryptic

    grep -w grow /tmp/test |wc -w

    where /tmp/test is:
    grrow grow grow
    old#<grown or young><growup

  4. #4
    quo
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    Quote Originally Posted by Salem View Post
    Something suitably cryptic...
    $ perl -n -e '$n = ( $_ =~ s/grow//g );print "$n\n";'
    old#<grown or young><growup
    2
    grow grow grow
    3
    Thank you for your answer.I have a few questions..
    Is this suitable for a bash script?
    Also I only want the substring <grow
    If there's a mere grow without the < in the front I dont want to count it.

  5. #5
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    How does you script looks like at the moment? Did you try it?
    Now if what you really want is to match the pattern /<grow/ then use this pattern instead of /grow/
    If you use grep, you would have to remove the -w switch.

  6. #6
    spurious conceit MK27's Avatar
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    Quote Originally Posted by quo View Post
    Thank you for your answer.I have a few questions..
    Is this suitable for a bash script?
    It is in the sense that perl is standard most (but not all) places bash is standard. It isn't in the sense that some people might call it heavy-handed.

    This is a fairly easy thing to do if you break the task into parts (which are hard to spot in one liners), and there are oodles of ways to do it. My advice is that you write a simple script to experiment with and start reading about the use of grep and sed. Might take you a bit longer than if you just cut n' paste someone else's code, but OTOH, next time you want to do something like this (it's also a fairly common kind of task) you'll have a better idea of how to go about it.
    C programming resources:
    GNU C Function and Macro Index -- glibc reference manual
    The C Book -- nice online learner guide
    Current ISO draft standard
    CCAN -- new CPAN like open source library repository
    3 (different) GNU debugger tutorials: #1 -- #2 -- #3
    cpwiki -- our wiki on sourceforge

  7. #7
    quo
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    Quote Originally Posted by mariostg View Post
    How does you script looks like at the moment? Did you try it?
    Now if what you really want is to match the pattern /<grow/ then use this pattern instead of /grow/
    If you use grep, you would have to remove the -w switch.
    It's just a test script so all it does is find the pattern /<grow/ in a file

    Code:
    #!/bin/bash
     
    grep '\<grow' ./test | wc -w
    for the following data(./test)

    <grow fffffff uuuuuuuu eeeeeeee<growup
    ddddddd iiiiiiii rrrrrrrr<growold <grow_hhhh grow
    grow<s yyyyyy vvvvvyoung><growgrow ccccc bbbbbbbold#<growup

    it should return 6 as the accepted are:


    <grow fffffff uuuuuuuu eeeeeeee<growup
    ddddddd iiiiiiii rrrrrrrr<growold <grow_hhhh grow
    grow<s yyyyyy vvvvvyoung><growgrow ccccc bbbbbbbold#<growup

    but it returns 14(the number of all the words)

  8. #8
    spurious conceit MK27's Avatar
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    Quote Originally Posted by quo View Post
    but it returns 14(the number of all the words)
    Right, because:

    Quote Originally Posted by man grep
    grep searches the named input FILEs (or standard input if no files are named, or if a single hyphen-minus (-) is given as file name) for lines containing a match to the given PATTERN. By default, grep prints the matching lines.
    If every line contains the pattern, grep will just output the entire file. Of course, you would notice this if you simply tried it on the command line . Fortunately:

    Quote Originally Posted by man grep
    -o, --only-matching
    Print only the matched (non-empty) parts of a matching line, with each such part on a separate output line.
    Which is why I suggested you read the manual, etc and do a little hands on experimenting. If you spend a little time learning to fish (anyone can do it), you'll save yourself time running around asking "Where are the fish?". Honestly.
    Salem likes this.
    C programming resources:
    GNU C Function and Macro Index -- glibc reference manual
    The C Book -- nice online learner guide
    Current ISO draft standard
    CCAN -- new CPAN like open source library repository
    3 (different) GNU debugger tutorials: #1 -- #2 -- #3
    cpwiki -- our wiki on sourceforge

  9. #9
    quo
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    Quote Originally Posted by MK27 View Post
    Which is why I suggested you read the manual, etc and do a little hands on experimenting. If you spend a little time learning to fish (anyone can do it), you'll save yourself time running around asking "Where are the fish?". Honestly.
    Yes you're right!Still trying to learn scripting.Thanks!

  10. #10
    - - - - - - - - oogabooga's Avatar
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    This can be done in "pure bash".
    Code:
    while read line ;do
      cnt=0
      while [ 1 ] ;do
        len=${#line}           # length of string
        line=${line/<grow//}   # substitute
        # if no change in length, break loop
        if [ ${#line} -eq $len ] ;then break ;fi
        let cnt++
      done
      let line_num++
      echo "Line $line_num: $cnt"
      let total=total+cnt
    done
    echo "Total: $total"
    MK27 likes this.
    The cost of software maintenance increases with the square of the programmer's creativity. - Robert D. Bliss

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