How do I Open This?

Jun 3, 2019 by Olaf Alders

When I’m working on code, I have to open a lot of files. I work primarily at the command line, inside a vim editor. On any given day I may need to translate some or all of the following into file paths that vim can understand:

• Stack traces
• Perl module names
• Perl module names suffixed with subroutine names
• git-grep results
• GitHub URLs

Figuring this stuff out isn’t generally that hard, but it can make your day just a little longer than it needs to be, so I wrote ot: a command line utility provided by Open::This.

I’ll be using vim in examples, but ot also supports nvim, emacs,nano and pico, defaulting to whatever you have set in $ENV{EDITOR}.

Following Along

I’ll be working out of a repository at https://github.com/oalders/git-helpers. If you’d like to follow along:

$ git clone https://github.com/oalders/git-helpers.git
$ cd git-helpers

Using a Perl Module Name

We’re now in the root of the git-helpers Git repository. Let’s say we want to open the Git::Helpers module. Translating a Perl module name into a file path isn’t all that hard. Given something like Git::Helpers, I know that I’m likely (but not always) looking for a file called Git/Helpers.pm. This could be in lib, t/lib or some custom directory. If I know exactly where to find this file, I can invoke vim directly:

$ vim lib/Git/Helpers.pm

However, if I’m not sure, or if I’m just lazy, this will get me to the same place:

ot Git::Helpers

This works because, by default, ot will search your lib and t/lib directories for local files. You can override this via the $ENV{OPEN_THIS_LIBS} variable. It accepts a comma-separated list of libs.

If the file can’t be found in one of the standard lib locations, ot will try to find an installed file on the system. So, if we’re not in the root of the git-helpers repository, but we’ve previously installed Git::Helpers from CPAN

$ ot Git::Helpers

might open open the following file: ~/.plenv/versions/5.26.1/lib/perl5/site_perl/5.26.1/Git/Helpers.pm.

Opening a Perl Module at a Subroutine Declaration

Let’s take this a step further. What if we want to open a file for a module but we also want to go straight to the correct subroutine declaration? Something like Git::Helpers::is_inside_work_tree(). We could probably craft a fancy one-liner to do this, but today we are lazy.

$ ot "Git::Helpers::is_inside_work_tree()"

That’s it. This will Do The Right Thing. (Note that in this case we had to quote the args to ot. Your shell will likely require this as well.)

We can do exactly the same thing for an installed module. Try this command:

$ ot "Test::More::subtest()"

In my case it opens /.plenv/versions/5.26.1/lib/perl5/site_perl/5.26.1/Test/More.pm at line 807, which is sub subtest {.

Opening a File Using a Line Number

Stack Traces

I see a lot of stack traces on any given day. A relevant chunk of a stack trace might look like: Died at lib/Git/Helpers.pm line 50.

Doing this by hand I might copy the file path and enter the following at the command line:

$ vim lib/Git/Helpers.pm

If I’m feeling fancy, I might translate the line number into something that vim understands:

$ vim +50 lib/Git/Helpers.pm

Or, I can just copy the file location and line number and feed it to ot:

$ ot lib/Git/Helpers.pm line 50

This will do the right thing and open lib/Git/Helpers.pm in vim at line 50.

git-grep

The results of some searches, like git grep, can contain line numbers as well as file names. To configure this behaviour in git use the following command:

$ git config --global grep.lineNumber true

If you don’t want to configure this directly in git you can also search via git grep --line-number foo.

Now that we’ve got line numbers in our git grep output, we can use its output to give hints to ot:

$ git grep 'sub _build_latest_release' .
lib/Git/Helpers/CPAN.pm:70:sub _build_latest_release {

Having run the above search, we can copy paste the results to ot:

$ ot lib/Git/Helpers/CPAN.pm:70

This will now open lib/Git/Helpers/CPAN.pm at line 70.

Opening a File at an Arbitrary Line and Column

As we saw above, ot can open files at the correct line number. Let’s get even lazier and have ot open our files at the correct line and column.

If you use the --vimgrep option with ripgrep then you will see column numbers as well as line numbers with your search results. For example:

$ rg --vimgrep '_build_latest_release' .
./lib/Git/Helpers/CPAN.pm:20:17:    builder => '_build_latest_release',
./lib/Git/Helpers/CPAN.pm:70:5:sub _build_latest_release {

To open lib/Git/Helpers/CPAN.pm at line 20 and column 17, simply copy/paste the rg output and pass it to ot:

$ ot ./lib/Git/Helpers/CPAN.pm:20:17

Opening Github Links Locally

Passing a full GitHub URL https://github.com/oalders/git-helpers/blob/master/lib/Git/Helpers.pm#L50, to ot will allow you to open the file locally, if it can be found in your relative file path.

$ ot https://github.com/oalders/git-helpers/blob/master/lib/Git/Helpers.pm#L50

opens lib/Git/Helpers.pm at line 50.

Passing a truncated URL path is also valid, if the path parts exist locally:

$ ot lib/Git/Helpers.pm#L50

Opening a Locally Checked Out File at GitHub

The -b flag will allow you to open your local files on GitHub.

Any of the following commands can launch a browser with a GitHub URL (hopefully) containing the file you want:

$ ot -b Git::Helpers
$ ot -b "Git::Helpers::is_inside_work_tree()"
$ ot -b Git::Helpers:75
$ ot -b Git::Helpers line 75

For example, from the top level of the git-helpers repository:

$ ot -b Git::Helpers:75

opens https://github.com/oalders/git-helpers/blob/master/lib/Git/Helpers.pm#L75.

Opening a File in Your $ENV{PATH}

ot can also be used as a shortcut to inspect files which can be found inside your $ENV{PATH}.

For example:

$ ot perldoc

opens ~/.plenv/versions/5.26.1/bin/perldoc on my machine. You can think of this as shorthand for:

$ which perldoc | xargs -o vim

Contributing

If you’d like to add support for more editors or other formats of data, please get in touch with me and we’ll see what we can do.

See Also

For other solutions to the problem of finding and opening files, I highly recommend fzf and fpp.