xmodmap
is the command to change the mouse button mapping:
xmodmap -e "pointer = 3 2 1"
will remap the first three buttoons, left, middle and right, to act like , right, middle and left - not actually changing the middle button mapping.
That applies the change to the current session - more precisely, to the current X display, for exanple :0
.
To save the change persistent over sessions, put the mapping into the file
~/.Xmodmap
If it does not exist, create it, liketouch ~/.Xmodmap
Edit it to add the line
pointer = 3 2 1
If there already is a pointer
line, it may have some function, of course; Instead of replacing it, better modify the first three values - keeping a comment with the old:
For example,
pointer = 1 2 3 4 5 16 17 8 9 10 11 12 13 14 15 6 7 18 19 20 21 22 23 24
becomes
!pointer = 1 2 3 4 5 16 17 8 9 10 11 12 13 14 15 6 7 18 19 20 21 22 23 24
pointer = 3 2 1 4 5 16 17 8 9 10 11 12 13 14 15 6 7 18 19 20 21 22 23 24
I'm used to ~/.Xmodmap
allways just working; But see .Xmodmap works only when automatic login disabled? if it does not.