From faf51d748e6567a74df43ef5bde4c2a02f813433 Mon Sep 17 00:00:00 2001
From: Tiago Cunha <tcunha@gmx.com>
Date: Thu, 29 Mar 2012 21:10:10 +0000
Subject: [PATCH] Sync OpenBSD patchset 1079:

Accept an argument to show-environment to show one variable, based on a
diff from Kazuhiko Sakaguchi.
---
 cmd-show-environment.c | 17 +++++++++++++++--
 tmux.1                 |  4 ++++
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/cmd-show-environment.c b/cmd-show-environment.c
index 9c065b22..1eb8fc31 100644
--- a/cmd-show-environment.c
+++ b/cmd-show-environment.c
@@ -31,8 +31,8 @@ int	cmd_show_environment_exec(struct cmd *, struct cmd_ctx *);
 
 const struct cmd_entry cmd_show_environment_entry = {
 	"show-environment", "showenv",
-	"gt:", 0, 0,
-	"[-g] " CMD_TARGET_SESSION_USAGE,
+	"gt:", 0, 1,
+	"[-g] " CMD_TARGET_SESSION_USAGE " [name]",
 	0,
 	NULL,
 	NULL,
@@ -55,6 +55,19 @@ cmd_show_environment_exec(struct cmd *self, struct cmd_ctx *ctx)
 		env = &s->environ;
 	}
 
+	if (args->argc != 0) {
+		envent = environ_find(env, args->argv[0]);
+		if (envent == NULL) {
+			ctx->error(ctx, "unknown variable: %s", args->argv[0]);
+			return (-1);
+		}
+		if (envent->value != NULL)
+			ctx->print(ctx, "%s=%s", envent->name, envent->value);
+		else
+			ctx->print(ctx, "-%s", envent->name);
+		return (0);
+	}
+
 	RB_FOREACH(envent, environ, env) {
 		if (envent->value != NULL)
 			ctx->print(ctx, "%s=%s", envent->name, envent->value);
diff --git a/tmux.1 b/tmux.1
index 1c60d9a2..61aa3d68 100644
--- a/tmux.1
+++ b/tmux.1
@@ -2912,12 +2912,16 @@ new process.
 .It Xo Ic show-environment
 .Op Fl g
 .Op Fl t Ar target-session
+.Op Ar variable
 .Xc
 .D1 (alias: Ic showenv )
 Display the environment for
 .Ar target-session
 or the global environment with
 .Fl g .
+If
+.Ar variable
+is omitted, all variables are shown.
 Variables removed from the environment are prefixed with
 .Ql - .
 .El