CASA accepts a variety of options through two mechanisms: configuration files and command line arguments. Configuration files are typically stored in a ~/.casa folder while command line options (only applicable to the full installation) are specified after the casa command at startup., rundata, logfile, nologfile, log2term, nologger, nogui, colors, agg, pipeline, iplog, telemetry_enabled, crashreporter_enabled)

Each modular CASA 6 package as well as the full installation reads a single configuration file. This file should be placed in the user root .casa folder (~/.casa) prior to starting the casa installation or importing the packages in to a standard python environment for the first time.

The following parameters can be set in the configuration file. Finer control over telemetry can also be set in the configuration file, as described here.

  • datapath : list of paths where CASA should search for data subdirectories

  • rundata : location of required runtime measures data, takes precedence over location(s) in datapath list

  • logfile : log file path/name

  • nologfile : do not create a log file when True, default False. If nologfile is true, then any logfile value is ignored and there is no log file.

  • log2term : print log output to terminal when True (in addition to any logfile and CASA logger), default False

  • nologger : do not start the CASA logger when True, default False

  • nogui : avoid starting GUI tools when True, default False. If nogui is True then the CASA logger is not started even if nologger is False.

  • colors : the IPython prompt color scheme. Must be one of “Neutral”, “NoColor”, “Linux” or “LightBG”, default “Neutral”. If an invalid color is given a warning message is printed and logged but CASA continues using the default color.

  • agg : startup without a graphical backend if True, default False

  • pipeline : attempt to load the pipeline modules and set other options appropriate for pipeline use if True, default False. When pipeline is True then agg will be assumed to be true even if agg is set to False here or on the command line.

  • iplog : create and use an IPython log in the current directory if True, default False.

  • telemetry_enabled : allow anonymous usage reporting, default True

  • crashreporter_enabled : allow anonymous crash reporting, default True

  • user_site : include the user’s local site-packages in the python path if True. Normally these are excluded to avoid any conflicts with CASA modules (when False, the default).

The configuration file is a standard python script, so any valid python syntax and libraries can be used. A typical file might look something like this:

datapath=["/home/casa/data/casa-data", "~/.casa/my_additional_data"]

An example file showing all recognized configurable parameters is shown here, this also illustrates that can contain other python commands. This shows setting logfile using the time module. Note that some of the parameters shown here are set to the their default values.

import time

datapath=["/home/casa/data/casa-data", "~/.casa/mydata"]
logfile='casalog-%s.log' % time.strftime("%Y%m%d-%H",time.localtime())
telemetry_enabled = True
crashreporter_enabled = True
nologfile = False
log2term = True
nologger = True
nogui = False
colors = "LightBG"
agg = False
pipeline = False
iplog = True
user_site = False
telemetry_log_directory = /tmp
telemetry_log_limit = 20000
telemetry_log_size_interval = 60
telemetry_submit_interval = 604800

At runtime the datapath(s) are expanded through a resolve(...) function to find the needed data tables. For example

>>> casatools.ctsys.resolve('geodetic/IERSpredict')


The command line arguments take precendence over the equivalent value.

The variables rundata and datapath are related but different. rundata is a single path, does not change after CASA has started, and it is meant to point to essential data that is required for CASA to run, such as the casacore Measures data (see External Data). In contrast, datapath is a list of paths and can be changed at runtime to include multiple data locations. The function resolve will search for files and directories through the datapath in list order. The idea is to allow users to add directories that contain the data they want to use during their session. After adding directories where they want to load data from, fully qualified paths are no longer needed for example for imaging tasks. Since there is no longer a single data path, users can add shared image directories, etc.

When using a monolithic/tar-file CASA distribution, if rundata is left as default, it points to the data included in the distribution. rundata can be used to set up and update custom data locations, see Updating a custom location. The value of rundata in a CASA session can be checked via the function rundata:

>>> casatools.ctsys.rundata()



rcdir is used to change the location of the root .casa folder to something other than ~/.casa. In addition to the startup files ( and the root .casa folder contains working files and directories used by CASA components (e.g. ipython, telemetry). It is expected to be writable by the user for use by those components.

This section only applies to the monolithic/tar-file CASA distribution, and it only applies to CASA 6.

For CASA 5, please see an earlier version of CASA Docs.

The '' file found in $HOME/.casa (i.e. ~/.casa/ is evaluated by the CASA shell just before the CASA prompt is presented to the user. This allows users to customize their CASA shell environment beyond the standard settings in '', by importing packages, setting variables or modifying the python system path.

One case where this is useful is for configuring CASA for ALMA data reduction. A package called 'analysisUtils' is often used as part of ALMA analysis. It is typically imported and instantiated in

$ cat ~/.casa/

import sys, os
import analysisUtils as aUes = aU.stuffForScienceDataReduction()

In this example, the standard python modules os and sys are made available in the CASA shell. The path where the analysisUtils module can be found is added to the Python system path, and finally the package is imported and an object is created. These modules and objects will then be available for the user within the CASA shell environment.


terminal(-h, --help, --logfile, --log2term, --nologger, --nologfile, --nogui, --rcdir, --norc, --colors, --pipeline, --agg, --iplog, --notelemetry, --nocrashreport, --datapath, --user-site, -v, --version, -c)

With the full installation of CASA from a tar file, the python environment itself is included and started through ./bin/casa. This ./bin/casa executable can be provided the following options to change configuration values at run time:

-h, --help            show this help message and exit
--logfile LOGFILE     path to log file
--log2term            direct output to terminal
--nologger            do not start CASA logger
--nologfile           do not create a log file
--nogui               avoid starting GUI tools
--rcdir RCDIR         location for startup files, internal working files
--norc                do not load user ( is unaffected)
--colors {Neutral,NoColor,Linux,LightBG} prompt color
--pipeline            load CASA pipeline modules on startup
--agg                 startup without graphical backend
--iplog               create ipython log
--notelemetry         disable telemetry collection
--nocrashreport       do not submit an online report when CASA crashes
--datapath DATAPATH   data path(s) [colon separated]
--user-site           include user's local site-packages lib in path
(toggling this option turns it on; use to append to the path)
-v, --version         show CASA version
-c ...                python eval string or python script to execute

These options take precedence over the configuration files. See the discussion of equivalent parameters for more details on these command line options.