http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_09_01
asctime()basename()catgets()crypt()ctime()dbm_clearerr()dbm_close()dbm_delete()dbm_error()dbm_fetch()dbm_firstkey()dbm_nextkey()dbm_open()dbm_store()dirname()dlerror()drand48()encrypt()endgrent()endpwent()endutxent()
ftw()getdate()getenv()getgrent()getgrgid()getgrnam()gethostent()getlogin()getnetbyaddr()getnetbyname()getnetent()getopt()getprotobyname()getprotobynumber()getprotoent()getpwent()getpwnam()getpwuid()getservbyname()getservbyport()getservent()
getutxent()getutxid()getutxline()gmtime()hcreate()hdestroy()hsearch()inet_ntoa()l64a()lgamma()lgammaf()lgammal()localeconv()localtime()lrand48()mblen()mbtowc()mrand48()nftw()nl_langinfo()ptsname()
putenv()pututxline()rand()readdir()setenv()setgrent()setkey()setlocale()setpwent()setutxent()strerror()strsignal()strtok()system()ttyname()unsetenv()wctomb()
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