EB double-grep function for bash

EB double-grep function for bash

[Tomas Nordin]

Emanuel Berg writes:

> Here is the function:
>
>     double-grep () {
>         local first=$1    # e.g., trim   (most unusual concept first!)
>         local second=$2   #       string (the the more usual...)
>
>         local context=$3  #  0 => no context: hits must be on same line
>         local results=$4  # 10 => show max 10 (double) hits
>
>         local -a files
>         files=($@[5,-1])  # e.g., ~/sw/emacs24-24.4+1/lisp/**/*.el
>
>         grep       --color=always -C $context $first  $files \
>             | grep --color=always             $second        \
>             | head -n $results
>
>         # invocation example:
>         #
>         #   $ cd ~/sw/emacs24-24.4+1/lisp/
>         #   $ double-grep trim string 0 10 **/*.el
>     }

Since the thread strayed away a little from emacs already... I made a
little change on two lines in this function to make it run with bash. (I
think the array subscript is a zsh thing). Here's the lines:

        local files
        files=${@:5:$#}  # e.g., ~/sw/emacs24-24.4+1/lisp/**/*.el

--
Tomas Nordin | (The computing freedom explorer)
GPG Key: AB09AF78

Re: EB double-grep function for bash

[Emanuel Berg]

Tomas Nordin wrote:

> Since the thread strayed away a little from
> emacs already...

Only superficially. The problem is how to find
a particular Emacs tool. The assumption is that
the user knows the conventional designation of
the tool and that the same designation is used
in Emacs. The answer what to do is as usual not
a single answer but a toolbox of methods in
itself, one of the tools proposed being greping
the Emacs source.

To do that we use the conventional shell tools
like grep, but one could easily think of
several others, e.g., awk, sed, even Perl.
To those who didn't know, grep is not only an
acronym-contraction, it was once a *command* in
one of the early line editors, for "global
regular expression print" - which makes sense!

I think I read this in either:

    @book{quarter-century-of-unix,
      title      = {A Quarter Century of UNIX},
      author     = {Peter Salus},
      publisher  = {Addison-Wesley},
      year       = 1994,
      ISBN       = 0201547775,
    }

or

    @book{sed-awk,
        title     = {sed \& awk},
        author    = {Dale Dougherty; Arnold Robbins},
        publisher = {O'Reilly},
        year      = 1997,
        edition   = {2nd edition},
        ISBN      = {1-56592-225-5},
    }

In Emacs, there is `grep', `grep-find', and so
on in

    /usr/share/emacs/24.4/lisp/progmodes/grep.el

    (or: /usr/share/emacs/24.4/lisp/progmodes/grep.el.gz)

That code is - advanced :)

> I made a little change on two
> lines in this function to make it run with
> bash. (I think the array subscript is a zsh
> thing). Here's the lines:
>
>         local files
>         files=${@:5:$#}

Cool :)

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