ref: d93553899706f68eb2406657f4a3e6f4d7cc6f89
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