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-rw-r--r--manual/startup.texi18
1 files changed, 13 insertions, 5 deletions
diff --git a/manual/startup.texi b/manual/startup.texi
index 1c75d3cabd..c8a525903b 100644
--- a/manual/startup.texi
+++ b/manual/startup.texi
@@ -317,6 +317,13 @@ definition is added to the environment. Otherwise, the @var{string} is
interpreted as the name of an environment variable, and any definition
for this variable in the environment is removed.
+The difference to the @code{setenv} function is that the exact string
+given as the parameter @var{string} is put into the environment. If the
+user should change the string after the @code{putenv} call this will
+reflect in automatically in the environment. This also requires that
+@var{string} is no automatic variable which scope is left before the
+variable is removed from the environment.
+
This function is part of the extended Unix interface. Since it was also
available in old SVID libraries you should define either
@var{_XOPEN_SOURCE} or @var{_SVID_SOURCE} before including any header.
@@ -329,11 +336,12 @@ available in old SVID libraries you should define either
The @code{setenv} function can be used to add a new definition to the
environment. The entry with the name @var{name} is replaced by the
value @samp{@var{name}=@var{value}}. Please note that this is also true
-if @var{value} is the empty string. A null pointer for the @var{value}
-parameter is illegal. If the environment already contains an entry with
-key @var{name} the @var{replace} parameter controls the action. If
-replace is zero, nothing happens. otherwise the old entry is replaced
-by the new one.
+if @var{value} is the empty string. To do this a new string is created
+and the strings @var{name} and @var{value} are copied. A null pointer
+for the @var{value} parameter is illegal. If the environment already
+contains an entry with key @var{name} the @var{replace} parameter
+controls the action. If replace is zero, nothing happens. Otherwise
+the old entry is replaced by the new one.
Please note that you cannot remove an entry completely using this function.