Chainsaw Build Status

Parses a log file and returns lines matching the time period provided. Chainsaw tries to be smart about determining the log format and parsing it accordingly. See the list of currently supported formats below.

Chronic is used to parse the time strings, so any format chronic supports, chainsaw supports. A list of supported formats can be found here:


gem install chainsaw


> chainsaw access.log 1 hour ago                  # entries from one hour ago to now
> chainsaw access.log august                      # entries from August to now
> chainsaw access.log 2012-08-06                  # entries from August 6th to now
> chainsaw access.log 2012-08-27 10:00            # entries from August 27th at 10:00 to now

# You can use a hypen to specify a time range (you can mix and match formats)

> chainsaw access.log 2012-08-01 - 2012-09-17     # entries within August 1st and September 17th
> chainsaw access.log august - yesterday          # entries within August and September


Additional text filter

You can specify an additional simple text pattern to filter (in addition to the time arguments) with the -f option.

> chainsaw access.log -f GET 1 hour ago

Colorize output

You can have chainsaw colorize the timestamp for easy scanning with the -c option.

> chainsaw access.log -c 1 hour ago

Interactive mode

If you want to print a line and wait for input (press return) before moving to the next found line, you can use the -i option.

> chainsaw access.log -i 1 hour ago

Output to a file

Chainsaw will output the found log lines to a file on the system if you specify with -o FILENAME.

> chainsaw access.log yesterday -o yesterday.log

Supported log formats (we think)

  • syslog
  • apache/nginx access (CLF)
  • apache error
  • nginx error
  • rack
  • rails
  • django
  • mongodb
  • redis
  • puppet
  • python logger
  • ruby logger


  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Added some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request