Merge branch 'richcarl/add-uptime-function'

* richcarl/add-uptime-function:
  Add uptime() shell command

OTP-12752

3 files changed, 32 insertions, 2 deletions

diff --git a/lib/stdlib/doc/src/c.xml b/lib/stdlib/doc/src/c.xml
index b49fa6ad67..b43d4786ae 100644
--- a/lib/stdlib/doc/src/c.xml
+++ b/lib/stdlib/doc/src/c.xml
@@ -232,6 +232,14 @@ compile:file(<anno>File</anno>, <anno>Options</anno> ++ [report_errors, report_w
       </desc>
     </func>
     <func>
+      <name name="uptime" arity="0"/>
+      <fsummary>Print node uptime</fsummary>
+      <desc>
+        <p>Prints the node uptime (as given by
+           <c>erlang:statistics(wall_clock)</c>), in human-readable form.</p>
+      </desc>
+    </func>
+    <func>
       <name>xm(ModSpec) -> void()</name>
       <fsummary>Cross reference check a module</fsummary>
       <type>
diff --git a/lib/stdlib/src/c.erl b/lib/stdlib/src/c.erl
index 9860adf04d..d5b24d3c32 100644
--- a/lib/stdlib/src/c.erl
+++ b/lib/stdlib/src/c.erl
@@ -27,7 +27,7 @@
 	 lc_batch/0, lc_batch/1,
 	 i/3,pid/3,m/0,m/1,
 	 bt/1, q/0,
-	 erlangrc/0,erlangrc/1,bi/1, flush/0, regs/0,
+	 erlangrc/0,erlangrc/1,bi/1, flush/0, regs/0, uptime/0,
 	 nregs/0,pwd/0,ls/0,ls/1,cd/1,memory/1,memory/0, xm/1]).
 
 -export([display_info/1]).
@@ -65,6 +65,7 @@ help() ->
 		   "q()        -- quit - shorthand for init:stop()\n"
 		   "regs()     -- information about registered processes\n"
 		   "nregs()    -- information about all registered processes\n"
+		   "uptime()   -- print node uptime\n"
 		   "xm(M)      -- cross reference check a module\n"
 		   "y(File)    -- generate a Yecc parser\n">>).
 
@@ -774,6 +775,26 @@ memory() -> erlang:memory().
 memory(TypeSpec) -> erlang:memory(TypeSpec).
 
 %%
+%% uptime/0
+%%
+
+-spec uptime() -> 'ok'.
+
+uptime() ->
+    io:format("~s~n", [uptime(get_uptime())]).
+
+uptime({D, {H, M, S}}) ->
+    lists:flatten(
+      [[ io_lib:format("~p days, ", [D]) || D > 0 ],
+       [ io_lib:format("~p hours, ", [H]) || D+H > 0 ],
+       [ io_lib:format("~p minutes and ", [M]) || D+H+M > 0 ],
+       io_lib:format("~p seconds", [S])]).
+
+get_uptime() ->
+    {UpTime, _} = erlang:statistics(wall_clock),
+    calendar:seconds_to_daystime(UpTime div 1000).
+
+%%
 %% Cross Reference Check
 %% 
 %%-spec xm(module() | file:filename()) -> xref:m/1 return
diff --git a/lib/stdlib/src/shell_default.erl b/lib/stdlib/src/shell_default.erl
index 3fe359af0e..0fca7ff8c7 100644
--- a/lib/stdlib/src/shell_default.erl
+++ b/lib/stdlib/src/shell_default.erl
@@ -23,7 +23,7 @@
 -module(shell_default).
 
 -export([help/0,lc/1,c/1,c/2,nc/1,nl/1,l/1,i/0,pid/3,i/3,m/0,m/1,
-         memory/0,memory/1,
+         memory/0,memory/1,uptime/0,
 	 erlangrc/1,bi/1, regs/0, flush/0,pwd/0,ls/0,ls/1,cd/1, 
          y/1, y/2,
 	 xm/1, bt/1, q/0,
@@ -92,6 +92,7 @@ pid(X,Y,Z) 	-> c:pid(X,Y,Z).
 pwd()           -> c:pwd().
 q()		-> c:q().
 regs()          -> c:regs().
+uptime()        -> c:uptime().
 xm(Mod)         -> c:xm(Mod).
 y(File)         -> c:y(File).
 y(File, Opts)   -> c:y(File, Opts).