# is x grep argument available?
grep-flag-available() {
    echo | grep $1 "" >/dev/null 2>&1
}

GREP_OPTIONS=""

# color grep results
if grep-flag-available --color=auto; then
    GREP_OPTIONS+=" --color=auto"
fi

# ignore VCS folders (if the necessary grep flags are available)
VCS_FOLDERS=".bzr,CVS,.git,.hg,.svn"
IDE_FOLDERS=".idea"
EXC_FOLDERS="{$VCS_FOLDERS,$IDE_FOLDERS}"

if grep-flag-available --exclude-dir=.cvs; then
    GREP_OPTIONS+=" --exclude-dir=$EXC_FOLDERS"
elif grep-flag-available --exclude=.cvs; then
    GREP_OPTIONS+=" --exclude=$EXC_FOLDERS"
fi

# export grep settings
alias grep="grep $GREP_OPTIONS"

# clean up
unset GREP_OPTIONS
unset VCS_FOLDERS
unset IDE_FOLDERS
unset EXC_FOLDERS
unfunction grep-flag-available