[SYMBOL] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [Q] [R] [S] [T] [U] [V] [W] [X] [Y] [Z] \U string escape \u string escape ualarm( ) uc( ) ucfirst( ) UDP (User Datagram Protocol) writing clients for writing servers for umask values uname( ) unbuffered input/output 2nd 3rd 4th undef( ), compared to delete( ) undefined values underscore (_), file stat cache Unicode character database combined characters, canonicalizing strings with converting Microsoft files to encodings, XML and named characters, using reading and writing from filehandles strings treating as octets treating as single characters Uniform Resource Locators [See URLs] unimport( ) unions of lists computing unique list elements, extracting universal character code UNIVERSAL module Unix domain sockets 2nd I/O layers unix layer 2nd UnixDate( ) unlink( ), removing directories and contents unpack( ) 2nd fixed-length records unread bytes, determining number unshift( ), circular lists updating random-access files uppercase, converting to lowercase URI::Escape module URI::Heuristic module 2nd uri_escape( ) urlify program URLs (Uniform Resource Locators) expanding tildes in filenames external redirection extracting from HTML fetching from Perl scripts putting HTML links around transparently storing information in use autouse pragma use bytes pragma use charnames pragma use constant pragma use lib pragma use locale pragma use operator use overload pragma use pragmas 2nd trapping errors in Usenet news messages User Datagram Protocol [See UDP] user interfaces adding text to images checking for waiting input clearing the screen controlling programs with Expect determining window size dialog boxes, creating with Tk DOS shell window, removing editing input full-screen mode graphing data 2nd managing screen manipulating terminal directly menus, creating with Tk multiscreen CGI scripts reading from keyboard reading passwords without echo ringing terminal bell tcapdemo program testing programs if running interactively text color thumbnailing images Tk resize events User::pwent module userstats program usleep( ) UTF-8 2nd utf8 I/O layer utime( ), timestamps |