=head1 NAME
-perlfaq8 - System Interaction ($Revision: 1.39 $, $Date: 1999/05/23 18:37:57 $)
+perlfaq8 - System Interaction ($Revision: 1.2 $, $Date: 2001/10/16 13:27:22 $)
=head1 DESCRIPTION
There's an example of this in L<perlfunc/crypt>). First, you put the
terminal into "no echo" mode, then just read the password normally.
You may do this with an old-style ioctl() function, POSIX terminal
-control (see L<POSIX> and Chapter 7 of the Camel, 2nd ed.), or a call
+control (see L<POSIX> or its documentation the Camel Book), or a call
to the B<stty> program, with varying degrees of portability.
You can also do this for most systems using the Term::ReadKey module
DEV->autoflush(1);
As mentioned in the previous item, this still doesn't work when using
-socket I/O between Unix and Macintosh. You'll need to hardcode your
+socket I/O between Unix and Macintosh. You'll need to hard code your
line terminators, in that case.
=item non-blocking input
# been opened on a pipe...
system("/bin/stty $stty");
$_ = <MODEM_IN>;
- chop;
+ chomp;
if ( !m/^Connected/ ) {
print STDERR "$0: cu printed `$_' instead of `Connected'\n";
}
You don't actually "trap" a control character. Instead, that character
generates a signal which is sent to your terminal's currently
foregrounded process group, which you then trap in your process.
-Signals are documented in L<perlipc/"Signals"> and chapter 6 of the Camel.
+Signals are documented in L<perlipc/"Signals"> and the
+section on ``Signals'' in the Camel.
Be warned that very few C libraries are re-entrant. Therefore, if you
attempt to print() in a handler that got invoked during another stdio
you're in a "slow" call, such as <FH>, read(), connect(), or
wait(), that the only way to terminate them is by "longjumping" out;
that is, by raising an exception. See the time-out handler for a
-blocking flock() in L<perlipc/"Signals"> or chapter 6 of the Camel, 2nd ed.
+blocking flock() in L<perlipc/"Signals"> or the section on ``Signals''
+in the Camel book.
=head2 How do I modify the shadow password file on a Unix system?
basis.) This mechanism will work for Unix, MS-DOS, Windows, and NT;
the VMS equivalent is C<set time>.
-However, if all you want to do is change your timezone, you can
+However, if all you want to do is change your time zone, you can
probably get away with setting an environment variable:
$ENV{TZ} = "MST7MDT"; # unixish
If you want finer granularity than the 1 second that the sleep()
function provides, the easiest way is to use the select() function as
documented in L<perlfunc/"select">. Try the Time::HiRes and
-the BSD::Itimer modules (available from CPAN).
+the BSD::Itimer modules (available from CPAN, and starting from
+Perl 5.8 Time::HiRes is part of the standard distribution).
=head2 How can I measure time under a second?
In general, you may not be able to. The Time::HiRes module (available
-from CPAN) provides this functionality for some systems.
+from CPAN, and starting from Perl 5.8 part of the standard distribution)
+provides this functionality for some systems.
If your system supports both the syscall() function in Perl as well as
a system call like gettimeofday(2), then you may be able to do
Perl's exception-handling mechanism is its eval() operator. You can
use eval() as setjmp and die() as longjmp. For details of this, see
the section on signals, especially the time-out handler for a blocking
-flock() in L<perlipc/"Signals"> and chapter 6 of the Camel 2nd ed.
+flock() in L<perlipc/"Signals"> or the section on ``Signals'' in
+the Camel Book.
If exception handling is all you're interested in, try the
exceptions.pl library (part of the standard perl distribution).
The IPC::Open2 module (part of the standard perl distribution) is an
easy-to-use approach that internally uses pipe(), fork(), and exec() to do
the job. Make sure you read the deadlock warnings in its documentation,
-though (see L<IPC::Open2>). See L<perlipc/"Bidirectional Communication
-with Another Process"> and L<perlipc/"Bidirectional Communication with
-Yourself">
+though (see L<IPC::Open2>). See
+L<perlipc/"Bidirectional Communication with Another Process"> and
+L<perlipc/"Bidirectional Communication with Yourself">
You may also use the IPC::Open3 module (part of the standard perl
distribution), but be warned that it has a different order of
=head2 How do I timeout a slow event?
Use the alarm() function, probably in conjunction with a signal
-handler, as documented in L<perlipc/"Signals"> and chapter 6 of the
-Camel. You may instead use the more flexible Sys::AlarmCall module
-available from CPAN.
+handler, as documented in L<perlipc/"Signals"> and the section on
+``Signals'' in the Camel. You may instead use the more flexible
+Sys::AlarmCall module available from CPAN.
=head2 How do I set CPU limits?
Copyright (c) 1997-1999 Tom Christiansen and Nathan Torkington.
All rights reserved.
-When included as part of the Standard Version of Perl, or as part of
-its complete documentation whether printed or otherwise, this work
-may be distributed only under the terms of Perl's Artistic License.
-Any distribution of this file or derivatives thereof I<outside>
-of that package require that special arrangements be made with
-copyright holder.
+This documentation is free; you can redistribute it and/or modify it
+under the same terms as Perl itself.
Irrespective of its distribution, all code examples in this file
are hereby placed into the public domain. You are permitted and
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