ref: b818f48f41895754dd9b470be407ba85cfea45bd
dir: /rc/bin/sysupdate/
#!/bin/rc
rfork en
cd /
if(! test -d .git)
bind -ac /dist/plan9front /
if(! ~ `{git/branch} heads/front)
>[1=2] echo sysupdate: must be on "front" branch to pull
if not
git/pull -u gits://git.9front.org/plan9front/plan9front