Many CASA options can be set in a .casarc file in the user's home directory.
~/.casarc
# SAMPLE .casarc FILE
# Set these so that bug(), ask(), etc. know who you are
userinfo.name: Sheila User
userinfo.email: suser@nrao.edu
userinfo.org: NRAO
# NOTE: Fill this value in as appropriate - the units are MB
# It is important that you not set this value larger than your actual physical memory
system.resources.memory: 2000
help.popup.type: mb3long
# Catalog
catalog.gui.auto: T
catalog.confirm: T
catalog.view.PostScript: ghostview
catalog.edit.ascii: xterm -e vi
# Logger
logger.file: ./aips++.log
logger.height: 12
logger.default: screen
# Progress meter GUI pop-ups - disable
progress.show: F
# Toolmanager - disable
toolmanager.gui.auto: F
# Use current working directory for cache/scratch files
user.aipsdir: .
user.cache: .
user.directories.work: .
user.initfiles: almainit.g
# Viewer
display.axislabels: on
display.colormaps.defaultcolormap: Hot Metal 1
# Development
ms.async: ddd ./ms %s
# Crash reporter - disable
UseCrashReporter: false