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From: Peter Lemenkov <lemenkov@gmail.com>
Date: Sat, 8 Nov 2014 15:11:04 +0300
Subject: [PATCH] Introduce os:getenv/2
Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>
diff --git a/lib/kernel/doc/src/os.xml b/lib/kernel/doc/src/os.xml
index 2b57e75..8b85f24 100644
--- a/lib/kernel/doc/src/os.xml
+++ b/lib/kernel/doc/src/os.xml
@@ -100,6 +100,19 @@ DirOut = os:cmd("dir"), % on Win32 platform</code>
</desc>
</func>
<func>
+ <name name="getenv" arity="2"/>
+ <fsummary>Get the value of an environment variable</fsummary>
+ <desc>
+ <p>Returns the <c><anno>Value</anno></c> of the environment variable
+ <c><anno>VarName</anno></c>, or <c>DefaultValue</c> if the environment variable
+ is undefined.</p>
+ <p>If Unicode file name encoding is in effect (see the <seealso
+ marker="erts:erl#file_name_encoding">erl manual
+ page</seealso>), the strings (both <c><anno>VarName</anno></c> and
+ <c><anno>Value</anno></c>) may contain characters with codepoints > 255.</p>
+ </desc>
+ </func>
+ <func>
<name name="getpid" arity="0"/>
<fsummary>Return the process identifier of the emulator process</fsummary>
<desc>
diff --git a/lib/kernel/src/os.erl b/lib/kernel/src/os.erl
index 187fd00..8aaf13b 100644
--- a/lib/kernel/src/os.erl
+++ b/lib/kernel/src/os.erl
@@ -26,7 +26,7 @@
%%% BIFs
--export([getenv/0, getenv/1, getpid/0, putenv/2, timestamp/0, unsetenv/1]).
+-export([getenv/0, getenv/1, getenv/2, getpid/0, putenv/2, timestamp/0, unsetenv/1]).
-spec getenv() -> [string()].
@@ -39,6 +39,19 @@ getenv() -> erlang:nif_error(undef).
getenv(_) ->
erlang:nif_error(undef).
+-spec getenv(VarName, DefaultValue) -> Value when
+ VarName :: string(),
+ DefaultValue :: string(),
+ Value :: string().
+
+getenv(VarName, DefaultValue) ->
+ case os:getenv(VarName) of
+ false ->
+ DefaultValue;
+ Value ->
+ Value
+ end.
+
-spec getpid() -> Value when
Value :: string().
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