Bash function to find contents of a file with a certain extension I have to read a lot of code and search through many code bases. I frequently find myself using something like grep -r --include=.C "test string" . to find files containing a certain string or regular expression. However, to simplify this and expedite the process, I want to create a function that allows me to specify what I am looking for, what are acceptable file extensions and what are inacceptable file extensions. 

The function I have written is below. I am not sure if this follows best practices. Also, the hack using the brace expansion with the .\? is bad. I really appreciate any feedback that you have.

findInFile() {
  # Function to be placed in bash profile
  # Allows user to specify what contents of a file they are looking for
  # in what file types and in what NOT file types
  # Iterate over the number of scripts arugments
  # TODO: How can I create documentation for this function outside of code comments?
  while [[ "$#" -gt 0 ]]
  do
    case $1 in
      -ft|--fileTypes)
        local fileTypes=$2
        ;;
      -et|--excludeTypes)
        local excludeTypes=$2
        ;;
      *) # Catch the case where user does not specify 
         # these arguments
        local searchTerm=$1
        ;;
    esac
    shift
  done

  echo "fileTypes: $fileTypes"
  echo "excludeTypes: $excludeTypes"
  echo "searchTerm: $searchTerm"

  # TODO: Should probably clean up with case statement
  # TODO: I am using this \? in the include and exclude as a hack
  # to catch the case where only one file type is provided. 
  if [ -n "$fileTypes" ] &amp;&amp; [ -n "$excludeTypes" ]
  then
    #searchString="grep -r --include=\*{$fileTypes} --exclude=\*{$excludeTypes} "$searchTerm" ."
    searchString="grep -r --include=\*{$fileTypes,.\?} --exclude=\*{$excludeTypes,.\?} "$searchTerm" ."

  elif [ -n "$fileTypes" ]
    then
      #searchString="grep -r --include=\*{$fileTypes} "$searchTerm" ."
      searchString="grep -r --include=\*{$fileTypes,.\?} "$searchTerm" ."
  elif [ -n "$excludeTypes" ]
    then
      #searchString="grep -r --exclude=\*{$excludeTypes} "$searchTerm" ."
      searchString="grep -r --exclude=\*{$excludeTypes,.\?} "$searchTerm" ."
  else
      searchString="grep -r "$searchTerm" ."
  fi

  #searchString="grep -r --include=\*{$fileTypes} "$searchTerm" ."
  echo "searchString: $searchString"
  eval $searchString

  # TODO: Allow the user to type a number to then programmatically jump to that
  # file in the text editor of their choice

}
You can use [[ .. ]] instead of [ .. ] to do tests.  The former is a bash builtin and saves a fork.

You don't need to eval anything since you're just building a couple of optional switches to grep.  Start with empty strings and populate variables or an array, and pass the result to an invocation of grep as variables.  This also avoids enumerating every possible combination of arguments (already 4 combos with 2 options -- that approach quickly becomes unsustainable).

There's no need to absorb searchTerm.  Just leave it in the arguments and pass all those to grep, which allows you to include grep switches too, like -i.

Use set +x to see what's going on.

Tying it all together:

findInFile() {
    :&lt;&lt;_comment_
        Function to be placed in bash profile
        Allows user to specify what contents of a file they are looking for
        in what file types and in what NOT file types
        Iterate over the number of scripts arugments
_comment_
    declare -a select
    while [[ "$#" -gt 0 ]]
    do
        if [[ $1 =~ ^(-ft|--fileTypes|-et|--excludeTypes)$ ]]
        then
            local type="$2"
            [[ "$type" == *,* ]] &amp;&amp; type="{$type}"
            if [[ $1 == *-f* ]]
            then 
                select+=( "--include=*$type" )
            else
                select+=( "--exclude=*$type" )
            fi
            shift 2
        else
            break
        fi
    done
    set -x
    grep -r ${select[@]} "$@" .
    { set +x; } 2&gt;/dev/null
}


You can include long comments as here-docs piped to the null operator :.