logfilter is a python application handy for real-time processing of very long log files.

Take the command tail -f, combine it with grep -e PATTER [-e PATTERN ...], and add a simple GUI enabling users to choose the log file to monitor and the filters to use: well, that is the essence of logfilter (or as other would say, logfilter in a nutshell).


  • Python with Tkinter support


logfilter can be installed using either the Bitbucket mercurial repository, or the Python Package Index (PyPI). If you feel lucky and you don't mind using a possibly unstable application in order to benefit of the latest project features, then choose the former. On the other hand, if you don't want to spend time filing bug reports due to crashing applications, then the latter would be definitely the better option (... I hope).

From sources:

cd /wherever/you/want
hg clone
python install

From the PyPI:

pip install logfilter


To give you an idea of the configuration options available for logfilter, this is the help of the application:

usage: logfilter [-h] [-s SLEEP_INTERVAL] [-l LIMIT] [-e FILTERS]
                [--font FONT] [--version]

Filter the content of a file, dynamically

positional arguments:
FILENAME              Filename to filter.

optional arguments:
-h, --help            show this help message and exit
                        Sleep SLEEP_INTERVAL seconds between iterations
-l LIMIT, --limit LIMIT
                        Number of lines to display in the text area
-e FILTERS, --regexp FILTERS
                        Filter presets
--font FONT           Font used by the application
--version             print the application version and quit

Don't be scared, you don't need to configure all of them to start the application; the GUI indeed, will let you customize them later. However, consider to use command line options to create handy aliases or shortcuts.

For example, imagine you are about to work with log files containing among the other things, Java stack traces. You could think about launching the application with the following options, in order to get notified as soon as a new exception (and relative stack trace) is added to the observed file:

python -e '([Ee]xception|\tat)' LOGFILE.log

Moreover, imagine you working on a new module being part of bigger project (all the log traces coming from such a module, have a special FOO keyword associated); then, to follow the live behavior of the module while still observing exceptional events coming from the rest of the application, you could start logfilter with the following options:

python -e '([Ee]xception|\tat)' -e FOO LOGFILE.log

Edit files

Since version 0.6.0dev, it is possible to configure logfilter to open the monitored file with an external editor.

The application will look for special environment variables (i.e. LFEDITOR first, then VISUAL and finally EDITOR) containing information regarding the external application to launch to edit the file at the line of interest.

For example, to make gvim your external editor, run logfilter as follows:

LFEDITOR="gvim FILE +ROW" logfilter LOGFILE.log -e FOO

Otherwise, if you are on Windows and prefer to use TextPad:

set LFEDITOR="C:\Programs\TextPad 4\TextPad.exe" FILE(ROW,0)& logfilter

The FILE and ROW markers will be automatically replaced by logfilter with the name of the monitored file and with the current selected line respectively.


0.8.0dev (2013-09-02):

  • ISSUE-31: it is now possible to add or remove filters dynamically at run-time (i.e. a new filter can be added focusing the text box containing the text <Add new>, while old ones can be removed by blanking their text box). Contenxtually with this change, the command line switches -f and --num-filters have been removed.
  • ISSUE-29: add popup entry to enable/disable passthru behaviour (i.e. display all the lines and highlight only those bits matching filters). Contextually, the command line switches -a and --catch-all have been removed.
  • The application does not quit anymore if the Escape key is pressed.
  • Add --version command line switch.

0.7.0dev (2012-12-08):

  • ISSUE-24: fix a bug where the selected text of the current line was not highlighted properly
  • ISSUE-27: add --font command line option to configure the font
  • ISSUE-28: fix a bug where multiple line end up being selected when a new line was rendered in the text widget
  • ISSUE-25: fix PY3K compatibility (there was a problem with local imports)

0.6.0dev (2012-12-01):

  • ISSUE-23: add popup menu entry to disable raise on output
  • ISSUE-19: add popup menu entry to enable line greedy coloring (multiple matches for the same filter in the same line)
  • ISSUE-21: add support for opening the current file in a configured external editor

0.5.0dev (2012-10-17):

  • ISSUE-18: add a catch-all filter (enabled with -a or --catch-all) which force the application to output all the lines of the file. Moreover, the lines matching filters expressions, will be highlighted as well
  • ISSUE-15: remember last user directory while opening the file chooser dialog multiple times
  • ISSUE-16: add a popup menu entry which disable the scroll on output behavior

0.4.0dev (2012-09-22):

  • Fix a bug where matched strings were not colored when the number of filters was greater than the size of the color palette
  • Install the application as a gui script (on Windows, do not open a cmd.exe)

0.3.1dev (2012-08-10):

  • Add right-click menu with an entry to clear the text widget (issue #10)
  • Better window focus management on new content read from the file (issue #12)
  • Add configuration setting to enable infinite scroll (issue #11)

0.2.1dev (2012-07-07):

  • Add python 3.2 compatibility

0.1.2dev (2012-06-27):

  • Better packaging (create a console script to run logfilter)

0.1.1 (2012-06-25):

  • Add file (issue #9)

0.1.0 (2012-06-02):

  • First public release