git: cbba9f7eeead - main - build(7): Document buildenv better

The branch main has been updated by imp:

URL: https://cgit.FreeBSD.org/src/commit/?id=cbba9f7eeead2f5c64e178d668dd314df70d7d56

commit cbba9f7eeead2f5c64e178d668dd314df70d7d56
Author:     Warner Losh <imp@FreeBSD.org>
AuthorDate: 2025-09-13 15:37:58 +0000
Commit:     Warner Losh <imp@FreeBSD.org>
CommitDate: 2025-09-13 15:38:33 +0000

    build(7): Document buildenv better
    
    Document the buildenvvars target and the BUILDENV_SHELL variable.
    
    Sponsored by:           Netflix
---
 share/man/man7/build.7 | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/share/man/man7/build.7 b/share/man/man7/build.7
index 4022b915c972..45a3034843d8 100644
--- a/share/man/man7/build.7
+++ b/share/man/man7/build.7
@@ -25,7 +25,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd August 8, 2025
+.Dd September 13, 2025
 .Dt BUILD 7
 .Os
 .Sh NAME
@@ -193,6 +193,20 @@ the compiler, linker, assembler, headers and libraries) has been
 built; see the
 .Cm toolchain
 target below.
+.Pp
+.Va BUILDENV_SHELL ,
+which defaults to
+.Pa /bin/sh ,
+is executed.
+This can be set to a command that does something in this build environment,
+like cross build an application.
+If that application has dependencies, though, the
+.Pa devel/poudriere
+package or port provides a more generic solution.
+.It Cm buildenvvars
+Print the shell variables that are set for a
+.Cm buildenv
+envirnoment and exit.
 .It Cm buildworld
 Build everything but the kernel, configure files in
 .Pa etc ,