If I want to find out how often I mentioned my flatmates Alberto and Melo in the same entry, I run
jrnl @alberto --tags | grep @melo
And will get something like @melo: 9, meaning there are 9 entries where both @alberto and @melo are tagged. How does this work? First, jrnl @alberto will filter the journal to only entries containing the tag @alberto, and then the --tags option will print out how often each tag occurred in this filtered journal. Finally, we pipe this to grep which will only display the line containing @melo.
You can do things like
jrnl @fixed -starred -n 10 -until "jan 2013" --short
To get a short summary of the 10 most recent, favourited entries before January 1, 2013 that are tagged with @fixed.
To use external editors for writing and editing journal entries, set them up in your .jrnl_config (see advanced usage for details). Generally, after writing an entry, you will have to save and close the file to save the changes to jrnl.
To use Sublime Text, install the command line tools for Sublime Text and configure your .jrnl_config like this:
"editor": "subl -w"
Note the -w flag to make sure jrnl waits for Sublime Text to close the file before writing into the journal.
Similar to Sublime Text, MacVim must be started with a flag that tells the the process to wait until the file is closed before passing control back to journal. In the case of MacVim, this is -f:
"editor": "mvim -f"
On OS X, you can use the fabulous iA Writer to write entries. Configure your .jrnl_config like this:
"editor": "open -b jp.informationarchitects.WriterForMacOSX -Wn"
What does this do? open -b ... opens a file using the application identified by the bundle identifier (a unique string for every app out there). -Wn tells the application to wait until it’s closed before passing back control, and to use a new instance of the application.
To set Notepad++ as your editor, edit the jrnl config file (.jrnl_config) like this:
"editor": "C:\\Program Files (x86)\\Notepad++\\notepad++.exe -multiInst",
The double backslashes are needed so jrnl can read the file path correctly. The -multiInst option will cause jrnl to open its own Notepad++ window.