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Some SED questions.

Discussion in 'Off Topic' started by WheresWaldo, Apr 23, 2019.

  1. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
    Staff Member

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    Need some Linux grep & sed help

    I need to read a file and search for a specific string. It the string does not exist I want to add it to the end of the file, if it does exist I want to replace the whole line I think I can do this all with a BASH script but don't exactly know how.

    Here is my example:

    Code:
    if grep -q 'firmwareupdater:' config.yaml
    then
      sed -i 's/avrdud_path:\(.*\)/avrdude_path: /usr/bin/avrdude/g config.yaml
    else
      cat config.yaml
    firmwareupdater:
      avrdude_path: /usr/bin/avrdude
    EOF
    fi
    
     
  2. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
    Staff Member

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    Just figured this out, the above code was just stupid and didn't work, but his code does.
    Code:
    #! /bin/bash
    
    if grep -Fq 'firmwareupdater:' config.yaml
    then
      sed -i 's|avrdud_path:.*|avrdude_path: /usr/bin/avrdude|g' config.yaml
      echo "line changed"
    else
      cat <<EOT >> config.yaml
    firmwareupdater:
      avrdude_path: /usr/bin/avrdude
    EOT
      echo "Lines added"
    fi
     
    mark tomlinson likes this.

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