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The {{getenv()}} function searches an environment list, provided by the host environment, for a string that matches a specified name.  The {{getenv()}} function returns a pointer to a string associated with the matched list member.  It is best not to store this pointer as it may be overwritten by a subsequent call to the {{getenv()}} function \[[ISO/IEC 9899-:1999|AA. C References#ISO/IEC 9899-1999]\] or invalidated as a result of changes made to the environment list through calls to {{putenv()}}, {{setenv()}}, or other means.  Storing the pointer for later use could result in a dangling pointer or a pointer to incorrect data.

According to C99 \[[ISO/IEC 9899-:1999|AA. C References#ISO/IEC 9899-1999]\]:

\[[ISO/IEC 9899-:1999|AA. C References#ISO/IEC 9899-1999]\] Section 7.20.4, "Communication with the environment"
\[[ISO/IEC PDTR 24731-2|AA. C References#ISO/IEC PDTR 24731-2-2007]\] 
\[[Open Group 04|AA. C References#Open Group 04]\] Chapter 8, "Environment Variables", [strdup|http://www.opengroup.org/onlinepubs/009695399/functions/strdup.html]
\[[Viega 03|AA. C References#Viega 03]\] Section 3.6, "Using Environment Variables Securely"