Use the pager given by the environment to display long output
Unix systems usually have a PAGER environment variable set.
If it is set, mercurial will use the pager application to display
output.
Two configuration variables are available to influence the behaviour of the
pager. ui.pager sets the pager application. The pager is
only used if ui.usepager is true. By default ui.usepager is disabled.
#!/bin/sh
# http://www.selenic.com/mercurial/bts/issue433
hg init a
cd a
echo a > a
hg commit -Ama
hg parents -r 0 doesnotexist
true