freebsd-update: open $PAGER only if necessary

[aryeeteygerald_rogers.com]

Summary

Previously, the $PAGER was opened even with no contents.
Applies patch to no longer do this.

PR: 194547,208497

Test Plan

Verified expected behaviour in interactive sh shell

[delphij]

I like this change in principle, but I think you could simplify the code a little bit (see my comments in line).

usr.sbin/freebsd-update/freebsd-update.sh

1953

Could you please refactor this to something like:

cat - modifiedfiles <<- EOF | ${PAGER}

The following files are affected by updates,
but no changes have
...
EOF

instead?

[aryeeteygerald_rogers.com]

• Use HEREDOC/cat instead of multiple echos

This is indeed much nicer.

[aryeeteygerald_rogers.com]

Remove unnecessary diff junk.

[delphij]

One last change request -- could you please use ${PAGER} instead of $PAGER while there? The change looks otherwise fine to me.

[emaste]

Forgot the review link; committed in rS343407