Cool Things to do in Emacs' Dired Mode

Delete some files in the Downloads folder

My Downloads folder is always out of control. There are always a ton of pdf files that I opened once in a browser but don't need to save. It's a pain to open a GUI file navigator, like Nautilus, and double click on each pdf file to view it and see if it should be tossed. However with Emacs, trimming my Downloads directory of old files is quick and easy.

Viewing Pdfs in Emacs

If you see a pdf with an uninformative name like 2010-09.pdf just hit <enter> when the cursor is on the file name, (when the file name is at point). Emacs will open the pdf in a new buffer. Once you have viewed the pdf and have decided its face you can quickly kill the pdf buffer with 'k' and you'll be returned to the directory. Now, if the pdf is unimportant, queue it to be deleted with 'd'. If you want to keep the file, but give it a better name, type 'R' to rename it. To unqueue a file for deletion, use 'u'. And finally to delete all the files currently queued for deletion, type 'x'.

Delete old Emacs backup files

If you have a lot of backup files that emacs created with ~ appended to the file name, you can quickly queue them all for deletion by typing '~'.

Here's the List of Directory Organizing Commands

key combo	command
<enter>	open file at point
d	Queue File For Deletion
u	Unqueue File
~	Queue Backup Files for Del
x	eXecute Queued Delete Jobs
R	Rename File
k	Kill PDF Buffer

Edit Zip'd or Tar-gz'd archives in place

If you need to edit a file inside a zip or tar archive, simply open the archive by hitting <enter> on the name in Dired mode, then click on the file. Edit the file and save it with 'C-x C-s', and then do another C-x C-s inside the zip buffer to save the archive with the file changes. The archive will be compressed again with your changes.

OMG!: Change File Owner, Group, Mode

key combo	command
O	change owner
M	change mode
G	change group
Z	compress file

Encrypt, Decrypt Files

Use ':e' to encrypt the file at point. Emacs will ask who you want to encrypt the file for (ie whose public key to use to encrypt the file.) You can also encrypt the file symmetrically with a password. Once the file is encrypted, there will be two files in the directory: the original file and the encrypted file with '.gpg' added to the file name.

Decrypt

To open the symmetrically encrypted file, click on its name and you will be prompted for a password. You can also type ':d' when the filename is at point.

EasyPG Assistant Docs

The program that is used to encrypt the file's is EasyPG Assistant. EasyPG Assistant Manual

Get More Help

Type 'C-hm' (describe mode) while in dired-mode, to pop open a help buffer, with a description of dired mode and a list of commands.

All Key Combinations named in post

key combo	command
d	mark file for deletion
u	unmark file
x	eXecute queued deletions
R	rename/move file
O	change owner
M	change mode
G	change group
Z	compress file
y	show only certain file type
w	copy file name
RET	open file at point
k	if in pdf buffer, kill
C-x C-s	Save file or archive
i	insert sub-directory
~	mark all backup files for deletion

Cool Things to do in Emacs' Dired Mode

Zombies, Emacs and Orgmode

I was playing around with Graphviz inside orgmode inside Emacs. Come the Zombie Apocalypse I'll be prepared, thanks to Emacs and Orgmode. Here's the Graphviz src:

digraph D {
  size="8,6"
  node [shape = polygon,
        sides = 4,
        distortion = "0.0",
        orientation = "0.0",
        skew = "0.0",
        color = "#aaaaaa",
        style = filled,
        fontname = "Helvetica-Outline" ];
  apocalypse [sides=9 skew=".32" color="purple"]
  apocalypse -> zombie
  apocalypse -> zombies
  shovel [skew=".56" color="#aa2222"]
  subgraph singular {
    label="one"
    color=purple
    zombie -> shovel [color="#440000"]
    shovel -> run
  }
  run [sides=9, color=salmon2];
  subgraph plural {
    label="many"
    color=red
    zombies -> run [color="#00a4d4"]
  }
}

save this file as zombies.gv, then run: graphviz zombies.gv.
If you are interested in graphviz, you can click on any graph in this gallery and see the graphviz source for the graph.

I wrote the graph source first in Emacs in Orgmode 7.5. Here's the src for experimenting with graphs in orgmode using the new org-babel, which lets you evaluate code in special code sections right inside of Emacs:

#+begin_src dot :file digraph2.png :cmdline -Kdot -Tpng  
digraph D {
  size="8,6"
 node [ shape = polygon,
  sides = 4,
  distortion = "0.0",
  orientation = "0.0",
  skew = "0.0",
  color = "#aaaaaa",
  style = filled,
  fontname = "Helvetica-Outline" ];
  apocalypse [sides=9 skew=".32" color="purple"]
  apocalypse -> zombie
  apocalypse -> zombies
  shovel [skew=".56" color="#aa2222"]
  subgraph singular {
    label="one"
    color=purple
    zombie -> shovel [color="#440000"]
    shovel -> run
  }
  run [sides=9, color=salmon2];
  subgraph plural {
    label="many"
    color=red
    zombies -> run [color="#00a4d4"]
  }
}
#+end_src

Then inside the buffer you can evaluate the code with "C-c C-c", and you can see the results of evaluating the code with "C-c C-o". This is made possible by Org-babel, a cool tool that allows you to run scripts from different languages in a single Org-mode buffer. Not only that but you can pipe output from one code block to another code block written in a different language. I will have more blog posts about this in the future. Org-babel is a part of Org-mode since Org-mode 7.x or so. Exciting stuff!

Further Reading

Org-babel Documentation
Graphviz

---

Edited with the emacs-chrome plugin

Updated the Scuttle Plugin to work with Firefox 4

I updated the Scuttle firefox plugin to work with Firefox 4. This was the one utility that was holding me back from upgrading to Firefox 4. I created a github repository. for the project. Feel free to fork the project. Its a good simple plugin if you’d like to learn how to write one.

The original scuttle firefox plugin hasn’t been upgraded since 2007. The version in This updated version is compatible with Firefox 4. You can view the source or fork the project at my github repository. or you can download the plugin directly: scuttle-0.4.2-firefox+fl.xpi

Scuttle is an open source Website Bookmarking System. I switched to it for my bookmarking needs after Yahoo! announced they were shutting down delicious.com. The cool thing about Scuttle is that its open source, (its written in PHP.) so you can download the source and run it on your own web server and if there's a new feature you want for your social bookmarking you can write it, also since it runs on your own server, you can be sure that the service will never end (just make regular backups.) The bad news is that you need to have a web server to run it. If you are just interested in an alternative to delicious you can try pinboard.in.

Also the credit goes to Marcus Campbell, original developer of scuttle and the scuttle plugin and also to Andreas Keller for originally updating the scuttle plugin for Firefox 3.

Updating Drupal Sites with Patches and Drush

I found a couple of drupal sites on a web server that were badly in need of security updates. They are no longer being maintained by a developer but they are still in use by a user community so I didn't like the idea of taking them down just because they are a security vulnerability, as they still have a great deal of value for people who use them. So I decided to update them with the patches that are available at fuerstnet.

If you follow the link above to fuerstnet, the site provides patches from all of the minor versions of drupal up to the most recent security level. So, if you check your drupal site's status at "admin/reports/status" (in drupal 6). And you see that you're drupal version is currently drupal 6.14. (That's 4 security releases out of date!) Then you can go to fuerstnet and download the drupal-6.14-to-6.18.patch security fixes only patch, or you can download the 6.14-to-to-6.20.patch (which includes bug fixes + security fixes.).

The first thing you need to do is make sure you have a current back-up of the database and the drupal file system.

1. Quick back-up of the file system:
cp -R DRUPAL_ROOT DRUPAL_ROOT-bk
2. Copy of database:
mysqldump -uDB-USER -p DB-NAME > ~/DRUPAL-SITE-NAME.db-backup-DATE.sql

or you can do the database back-up with drush:
drush sql-dump --result-file=~/DRUPAL-SITE-NAME.db_backup-DATE.sql
Of course, you need to replace all of the ALL_CAPS names up above with the names that correspond with your site. Now on to the update procedure:

The procedure, as outlined at fuerstnet, is:
1. copy the patch into you're drupal root directory.
2. put your site into maintenance mode. "admin/settings/site-maintenance" (in drupal 6)
3. cd into the DRUPAL_ROOT directory.
4. patch -p1 --dry-run < DRUPALPATCH
(replace DRUPALPATCH with the name of your patch, ie drupal-6.14-to-6.20.patch) if you do not see any errors in the output of the patch command, then you can run the command again for real.
5. patch -p1 < DRUPALPATCH
Next you have to run update.php, which if you have drush you can run like so:
6. drush updatedb
or you can visit http://YOUR-DRUPAL-SITE/update.php
7. next: test your site, update any modules that need updating and then don't forget to pull your site out of maintenance mode.

Another possibility is to run the upgrades in drush with the shell command:
> drush pm-update --security-only

This command will update your site with any available security updates. It will first show you a list of updates that are available and ask if you if you want to proceed. You must answer y or n. This command is great, because you can run it in the root directory of any of your drupal sites and it will show you which updates are available. Also if you have site-aliases set up, you can run it against all of your aliases one at a time and you don't have to leave the comfort of your /home directory!

> drush @dev pm-update --security-only
(where @dev is an alias name for one of your sites.)

Of course you can run the update command without the --security-only and it will offer to update all of your modules, themes and core drupal files.

[However I ran into trouble with this approach as it updated the themes as well on one of the sites I was updating and the original site developer had customized the theme instead of creating a new them and customizing that! So I restore the theme from backup. Of course when drush updates modules and themes it backs up the old ones in a directory outside the drupal directory, so if there is a mishap, such as overwriting a customized theme, you can restore and clear cache to restore the old theme. Although there is that safety net, I still now prefer to update security-fixes only at first, and then run non-security modules fixes one at a time and run the theme fixes manually. Schwew, big aside.]

After running the drush pm-update, which can be shortened to drush up, I like to run a quick:
> drush updatedb
to make sure the database has been updated properly, and:
> drush cc all
to make sure the caches are cleared.

And once you have all of your sites aliased, it is simple to ssh into your web server and run the drush up --security-only command once a week to check that all of your sites are up to date with the security fixes.

Emacs Window Commands

I recently bought a new large monitor, which opened the possibility of using Emacs with multiple, side-by-side windows. Which is brilliant by the way! Since I plugged it in, I've been "C-x 3"-ing like a madman. My new favorite way to learn programming is having an info file open in the left window and in the right window having a scheme (or python) prompt open. That is what I am doing now working on the Structure and Interpretation of Computer Programs. Luckily there was an info file available. I'm trying to think of a simple way to translate my programming epubs or pdfs into info files.

Anyways on to todays topic. Emacs window commands!

The first thing to keep in mind, is the difference between windows and frames in emacs. To emacs: a window is any portal to a buffer. if you type in "C-x 2" in emacs and your view splits in half. These two portals are known as windows. What we usually call a new window, is known as a frame to emacs. So when you type in Ctrl-n in your browser and a new window pops open, in Emacsia, this is known as a new frame.

Open another window:

C-x 2 open another vertical window.
C-x 3 open another horizontal window.
C-x 4 b open a buffer in the other window
C-x 4 f open a new file in the other window.
C-x 1 close all other windows, leave current window open.
C-x 0 close current window, switch to other window.
C-x o move to other window

Positioning windows:

C-x + balance windows. This balances the size of all open windows.
C-x { widen current window.
C-x } narrow current window.
C-u C-x { widen current window by 4 columns.
C-u C-x } narrow current window by 4 columns.

Scroll other window:

M-C-v scroll other window