mysql hostname prompt when host is localhost

mysql hostname prompt when host is localhost: "
I manage several mysql servers and often on these servers for security reasons the SUPER account is not allowed external network access, so access is made to localhost. When connecting to several hosts at the same time, for example from different ssh sessions, this can be inconvenient as the \h prompt only ever shows localhost and not the hostname of the server to which I’m connected.

The following small patch against 5.1.36 which can also be found here adds a new \H option which behaves the same as \h except in this case the hostname is shown.

diff --git a/Docs/mysql.info b/Docs/mysql.info
index 7747201..dffacfd 100644
--- a/Docs/mysql.info
+++ b/Docs/mysql.info
@@ -20512,6 +20512,8 @@ sequences.
`\D'        The full current date
`\d'        The default database
`\h'        The server host
+`\H'        Same as `\h' except that if the server host is localhost
+            the client's hostname will be used
`\l'        The current delimiter (new in 5.1.12)
`\m'        Minutes of the current time
`\n'        A newline character
diff --git a/client/mysql.cc b/client/mysql.cc
index 5f360b8..b24fb14 100644
--- a/client/mysql.cc
+++ b/client/mysql.cc
@@ -39,6 +39,10 @@
#include <signal.h>
#include <violite.h>

+#ifdef SOLARIS
+extern "C" int gethostname(char *name, int namelen);
+#endif
+
#if defined(USE_LIBEDIT_INTERFACE) && defined(HAVE_LOCALE_H)
#include <locale.h>
#endif
@@ -4657,12 +4661,27 @@ static const char* construct_prompt()
case 'd':
processed_prompt.append(current_db ? current_db : "(none)");
break;
+      /* \H is the same as \h except if \h returns localhost in which case *
+       * we provide the client's hostname.                                 *
+       */
case 'h':
+      case 'H':
{
const char *prompt;
+        char  myhostname[255];
prompt= connected ? mysql_get_host_info(&mysql) : "not_connected";
-    if (strstr(prompt, "Localhost"))
-      processed_prompt.append("localhost");
+
+    if (strstr(prompt, "Localhost") || strstr(prompt, "localhost"))
+          if ( *c == 'h' ) {
+        processed_prompt.append("localhost");
+          }
+          else
+          {
+            if (gethostname(myhostname,sizeof(myhostname)) < 0)
+              processed_prompt.append( "gethostname(3) returned an error" );
+            else
+              processed_prompt.append( myhostname );
+          }
else
{
const char *end=strcend(prompt,' ');

This gives the output as shown below:

$ hostname
my.computer.domain.com
$ client/mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 6892
Server version: 5.0.xx MySQL Community Server (GPL)

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> prompt \h
PROMPT set to '\h '
localhost prompt \H
PROMPT set to 'prompt \H '
prompt my.computer.domain.com quit
Bye
$

As this uses the FQDN it may be necessary to add another option to show only the host’s short name but for now this patch is useful for me. I expect the patch should work against most other versions of MySQL. Perhaps this is useful enough to warrant putting in the main MySQL sources?

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