add DH_QUIET environment variable

Add a DH_QUIET environment variable to make debhelper more silent
if set (unless DH_VERBOSE is set).
Add new helper functions print_and_doit, print_and_doint_noerror,
and nonquiet_print.
If DH_QUIET is set, disable printing of dh subcommands to be run.
Describe effects DH_QUIET should have in doc/PROGRAMMING.

1 files changed, 3 insertions, 1 deletions

diff --git a/dh b/dh
index ece00c41..eceb62e9 100755
--- a/dh
+++ b/dh
@@ -713,7 +713,9 @@ sub run {
 
 	# 3 space indent lines the command being run up under the
 	# sequence name after "dh ".
-	print "   ".escape_shell($command, @options)."\n";
+	if (!$dh{QUIET}) {
+		print "   ".escape_shell($command, @options)."\n";
+	}
 
 	return if $dh{NO_ACT};