0027
umask var = 0027
u=rwx,g=rx,o=

running umask a-r
0777
u=,g=,o=

running umask u+x
0677
u=x,g=,o=

running umask g+rwx,o+x
0706
u=,g=rwx,o=x

running umask u-w,o-x
0201
u=rx,g=rwx,o=rw

running umask a-r
0444
u=wx,g=wx,o=wx

running umask ug-rx
0550
u=w,g=w,o=rwx

running umask u+r,g+w,o=rw
0351
u=r,g=w,o=rw

running umask =r,g+w,o+x,o-r
0316
u=r,g=rw,o=x

running umask rx
0222
u=rx,g=rx,o=rx