[PATCH 1/3] cmd/nvedit.c: teach 'env default' to optionally keep runtime variables

[Rasmus Villemoes <ravi@prevas.dk>]

It can be useful to set all variables defined in the default
environment to the value they have there, but without removing
variables that are only defined at runtime. This can sort-of be done
today, by using the "env default var1 var2 ..." variant, but that
requires listing all variables defined in the default
environment. It's much more convenient to be able to say

  env default -k -a

The -k flag is also meaningful in the other case: If var1 is not
defined in the default environment, but var2 is,

  env default var1 var2

would emit a warning about var1 not being in the default env and thus
being deleted. With -k, there's no warning, and var1 is kept as-is.

Signed-off-by: Rasmus Villemoes <ravi@prevas.dk>
---
 cmd/nvedit.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/cmd/nvedit.c b/cmd/nvedit.c
index 392f90f8698..1f259801293 100644
--- a/cmd/nvedit.c
+++ b/cmd/nvedit.c
@@ -523,6 +523,9 @@ static int do_env_default(struct cmd_tbl *cmdtp, int flag,
 			case 'f':		/* force */
 				env_flag |= H_FORCE;
 				break;
+			case 'k':
+				env_flag |= H_NOCLEAR;
+				break;
 			default:
 				return cmd_usage(cmdtp);
 			}
@@ -1133,8 +1136,9 @@ U_BOOT_LONGHELP(env,
 #if defined(CONFIG_CMD_ENV_CALLBACK)
 	"callbacks - print callbacks and their associated variables\nenv "
 #endif
-	"default [-f] -a - [forcibly] reset default environment\n"
-	"env default [-f] var [...] - [forcibly] reset variable(s) to their default values\n"
+	"default [-k] [-f] -a - [forcibly] reset default environment\n"
+	"env default [-k] [-f] var [...] - [forcibly] reset variable(s) to their default values\n"
+	"      \"-k\": keep variables not defined in default environment\n"
 	"env delete [-f] var [...] - [forcibly] delete variable(s)\n"
 #if defined(CONFIG_CMD_EDITENV)
 	"env edit name - edit environment variable\n"
-- 
2.47.0