gcalcli HowTo (taken from gcalcli wiki)

How to use gcalcli...

Login Information
You can provide gcalcli with your Google Calendar login information either by editing the top of the script itself, using the --user and --pw arguments, or using the config file. In any case make sure you protect the information.

HTTP Proxy Support

gcalcli will automatically work with an HTTP Proxy simply by setting up some environment variables:

   http_proxy
   https_proxy
   proxy-username
   proxy-password
Note that these environment variables must be lowercase and beware the usage of the dashes vs underscores.

Config File

gcalcli is able to read default configuration information from a config file. This file is location at '~/.gcalclirc' and must be formatted as follows:

   [gcalcli]
   <config-item>: <value>
   <config-item>: <value>
   ...
The available config items are the same as those that can be specified on the command line. Note that any value specified on the command line overrides the config file.

   user: <username>
   pw: <password>
   cals: <type>
   details: <true|false>
   ignore-started: <true|false>
   width: <width>
   cal-owner-color: <color>
   cal-editor-color: <color>
   cal-contributor-color: <color>
   cal-read-color: <color>
   cal-freebusy-color: <color>
   date-color: <color>
   border-color: <color>

'gcalcli' event popup reminders using cron
Run gcalcli using cron and generate xmessage-like popups for reminders.
   % crontab -e
Then add the following line:
   */10 * * * * gcalcli remind

'gcalcli' agenda on your root desktop
Put your agenda on your desktop using Conky. Add the following to your .conkyrc:
   ${execi 300 gcalcli --nc agenda}
To also get a graphical calendar that shows the next three weeks add:
   ${execi 300 gcalcli --nc --cals=owner calw 3}

'gcalcli' agenda integration with 'screen'
Put your next event in your 'screen' hardstatus line. First add a cron job that will dump you agenda to a text file:
   % crontab -e
Then add the following line:
   */5 * * * * gcalcli --nc --ignore-started agenda "`date`" > /tmp/gcalcli_agenda.txt
Next create a simple shell script that will extract the first agenda line. Let's call this script 'screen_agenda':
   #!/bin/bash
   head -2 /tmp/gcalcli_agenda.txt | tail -1
Next configure screen's hardstatus line to gather data from a backtick command. Of course your hardstatus line is most likely very different than this (Mine is!):
   backtick 1 60 60 screen_agenda
   hardstatus "[ %1` ]"

'gcalcli' Usage
Usage:

gcalcli [options] command [command args]

 Options:

  --help                   this usage text

  --config <file>          config file to read (default is '~/.gcalclirc')

  --user <username>        google username

  --pw <password>          password

  --cals=[all,             'calendars' to work with (default is all calendars)
          default,         - default (your default main calendar)
          owner,           - owner (your owned calendars)
          editor,          - editor (editable calendar)
          contributor,     - contributor (non-owner but able to edit)
          read,            - read (read only calendars)
          freebusy]        - freebusy (only free/busy info visible)

  --cal=<name>             'calendar' to work with (default is all calendars)
                           - you can specify a calendar by name or by using a
                             regular expression to match multiple calendars
                           - you can use multiple '--cal' arguments on the
                             command line

  --details                show all event details (i.e. length, location,
                           reminders, contents)

  --ignore-started         ignore old or already started events
                           - when used with the 'agenda' command, ignore events
                             that have already started and are in-progress with
                             respect to the specified [start] time
                           - when used with the 'search' command, ignore events
                             that have already occurred and only show future
                             events

  --width                  the number of characters to use for each column in
                           the 'cal' command output (default is 10)

  --nc                     don't use colors

  --cal-owner-color        specify the colors used for the calendars and dates
  --cal-editor-color       each of these argument requires a <color> argument
  --cal-contributor-color  which must be one of [ default, black, brightblack,
  --cal-read-color         red, brightred, green, brightgreen, yellow,
  --cal-freebusy-color     brightyellow, blue, brightblue, magenta,
  --date-color             brightmagenta, cyan, brightcyan, white,
  --border-color           brightwhite ]

 Commands:

  list                     list all calendars

  search <text>            search for events
                           - only matches whole words

  agenda [start] [end]     get an agenda for a time period
                           - start time default is 12am today
                           - end time default is 5 days from start
                           - example time strings:
                              '9/24/2007'
                              'Sep 24 2007 3:30pm'
                              '2007-09-24T15:30'
                              '2007-09-24T15:30-8:00'
                              '20070924T15'
                              '8am'

  calw <weeks> [start]     get a week based agenda in a nice calendar format
                           - weeks is the number of weeks to display
                           - start time default is beginning of this week
                           - note that all events for the week(s) are displayed

  calm [start]             get a month agenda in a nice calendar format
                           - start time default is the beginning of this month
                           - note that all events for the month are displayed
                             and only one month will be displayed

  quick <text>             quick add an event to default calendar
                           - example:
                              'Dinner with Eric 7pm tomorrow'
                              '5pm 10/31 Trick or Treat'

  remind <mins> <command>  execute command if event occurs within <mins>
                           minutes time ('%s' in <command> is replaced with
                           event start time and title text)
                           - <minutes> default is 10
                           - default command:
                              'gxmessage -display :0 -center \
                                         -title "Ding, Ding, Ding!" %s'