Since you don't have a C compiler, you're doomed and your vendor
should be sacrificed to the Sun gods. But that doesn't help you.
-What you need to do is get a binary version of gcc for your system
+What you need to do is get a binary version of C<gcc> for your system
first. Consult the Usenet FAQs for your operating system for
information on where to get such a binary version.
approaches are doomed to failure.
One simple way to check that things are in the right place is to print out
-the hard-coded @INC that perl looks through for libraries:
+the hard-coded C<@INC> that perl looks through for libraries:
% perl -le 'print for @INC'
If this command lists any paths that don't exist on your system, then you
may need to move the appropriate libraries to these locations, or create
-symbolic links, aliases, or shortcuts appropriately. @INC is also printed as
+symbolic links, aliases, or shortcuts appropriately. C<@INC> is also printed as
part of the output of
% perl -V
Read the F<INSTALL> file, which is part of the source distribution.
It describes in detail how to cope with most idiosyncrasies that the
-Configure script can't work around for any given system or
+C<Configure> script can't work around for any given system or
architecture.
=head2 What modules and extensions are available for Perl? What is CPAN? What does CPAN/src/... mean?
to the most frequently asked questions about CPAN including how to
become a mirror.
-CPAN/path/... is a naming convention for files available on CPAN
+C<CPAN/path/...> is a naming convention for files available on CPAN
sites. CPAN indicates the base directory of a CPAN mirror, and the
rest of the path is the path from that directory to the file. For
instance, if you're using ftp://ftp.funet.fi/pub/languages/perl/CPAN
-as your CPAN site, the file CPAN/misc/japh is downloadable as
+as your CPAN site, the file C<CPAN/misc/japh> is downloadable as
ftp://ftp.funet.fi/pub/languages/perl/CPAN/misc/japh .
Considering that, as of 2006, there are over ten thousand existing
modules in the archive, one probably exists to do nearly anything you
-can think of. Current categories under CPAN/modules/by-category/
+can think of. Current categories under C<CPAN/modules/by-category/>
include Perl core modules; development support; operating system
interfaces; networking, devices, and interprocess communication; data
type utilities; database interfaces; user interfaces; interfaces to
If you have Perl installed locally, you probably have the documentation
installed as well: type C<man perl> if you're on a system resembling Unix.
This will lead you to other important man pages, including how to set your
-$MANPATH. If you're not on a Unix system, access to the documentation
+C<$MANPATH>. If you're not on a Unix system, access to the documentation
will be different; for example, documentation might only be in HTML format. All
proper perl installations have fully-accessible documentation.
You might also try C<perldoc perl> in case your system doesn't
-have a proper man command, or it's been misinstalled. If that doesn't
-work, try looking in /usr/local/lib/perl5/pod for documentation.
+have a proper C<man> command, or it's been misinstalled. If that doesn't
+work, try looking in C</usr/local/lib/perl5/pod> for documentation.
If all else fails, consult http://perldoc.perl.org/ which has the
complete documentation in HTML and PDF format.
Writing Perl Modules for CPAN
by Sam Tregar
- ISBN 1-59059-018-X [1st edition Aug 2002]
+ ISBN 1-59059-018-X [1st edition August 2002]
http://apress.com/book/bookDisplay.html?bID=14
The Perl Cookbook
http://www.awlonline.com/
Object Oriented Perl
- Damian Conway
+ by Damian Conway
with foreword by Randal L. Schwartz
ISBN 1-884777-79-1 [1st edition August 1999]
http://www.manning.com/conway/
Data Munging with Perl
- Dave Cross
+ by Dave Cross
ISBN 1-930110-00-6 [1st edition 2001]
http://www.manning.com/cross
another language). There's also I<$foo Magazin>, a german magazine
dedicated to Perl, at ( http://www.foo-magazin.de ).
+The I<Perl-Zeitung> is a German-speaking magazine for Perl beginners
+(see http://perl-zeitung.at.tf ).
+
Magazines that frequently carry quality articles on Perl include I<The
Perl Review> ( http://www.theperlreview.com ), I<Unix Review> (
http://www.unixreview.com/ ), I<Linux Magazine> (
http://www.linuxmagazine.com/ ), and Usenix's newsletter/magazine to
-its members, I<login:> ( http://www.usenix.org/ )
+its members, I<login:> ( http://www.usenix.org/ ).
The Perl columns of Randal L. Schwartz are available on the web at
http://www.stonehenge.com/merlyn/WebTechniques/ ,
studies, announcements, contests, and much more. I<TPJ> has columns
on web development, databases, Win32 Perl, graphical programming,
regular expressions, and networking, and sponsors the Obfuscated Perl
-Contest and the Perl Poetry Contests. Beginning in November 2002, TPJ
+Contest and the Perl Poetry Contests. Beginning in November 2002, I<TPJ>
moved to a reader-supported monthly e-zine format in which subscribers
-can download issues as PDF documents. In 2006, TPJ merged with Dr.
-Dobbs Journal (online edition). To read old TPJ articles, see
+can download issues as PDF documents. In 2006, I<TPJ> merged with Dr.
+Dobbs Journal (online edition). To read old I<TPJ> articles, see
http://www.ddj.com/ .
=head2 What mailing lists are there for Perl?
-Most of the major modules (Tk, CGI, libwww-perl) have their own
+Most of the major modules (C<Tk>, C<CGI>, C<libwww-perl>) have their own
mailing lists. Consult the documentation that came with the module for
subscription information.
use the C<Module::CoreList> module. It has the information about
the modules (with their versions) included with each release of Perl.
+If C<Module::CoreList> is not installed on your system, check out
+http://perlpunks.de/corelist .
+
Every CPAN module has a bug tracker set up in RT, http://rt.cpan.org .
You can submit bugs to RT either through its web interface or by
email. To email a bug report, send it to
=head2 How do I find out which operating system I'm running under?
-The $^O variable ($OSNAME if you use English) contains an indication of
+The C<$^O> variable (C<$OSNAME> if you use C<English>) contains an indication of
the name of the operating system (not its release number) that your perl
binary was built for.
In general, you don't, because you don't know whether
the recipient has a color-aware display device. If you
know that they have an ANSI terminal that understands
-color, you can use the Term::ANSIColor module from CPAN:
+color, you can use the C<Term::ANSIColor> module from CPAN:
use Term::ANSIColor;
print color("red"), "Stop!\n", color("reset");
sysread(TTY, $key, 1); # probably this does
system "stty -cbreak </dev/tty >/dev/tty 2>&1";
-The Term::ReadKey module from CPAN offers an easy-to-use interface that
+The C<Term::ReadKey> module from CPAN offers an easy-to-use interface that
should be more efficient than shelling out to B<stty> for each key.
It even includes limited support for Windows.
However, using the code requires that you have a working C compiler
and can use it to build and install a CPAN module. Here's a solution
-using the standard POSIX module, which is already on your systems
+using the standard C<POSIX> module, which is already on your systems
(assuming your system supports POSIX).
use HotKey;
$key = readkey();
-And here's the HotKey module, which hides the somewhat mystifying calls
+And here's the C<HotKey> module, which hides the somewhat mystifying calls
to manipulate the POSIX termios structures.
# HotKey.pm
=head2 How do I check whether input is ready on the keyboard?
The easiest way to do this is to read a key in nonblocking mode with the
-Term::ReadKey module from CPAN, passing it an argument of -1 to indicate
+C<Term::ReadKey> module from CPAN, passing it an argument of -1 to indicate
not to block:
use Term::ReadKey;
=head2 How do I get the screen size?
-If you have Term::ReadKey module installed from CPAN,
+If you have C<Term::ReadKey> module installed from CPAN,
you can use it to fetch the width and height in characters
and in pixels:
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
+You may do this with an old-style C<ioctl()> function, POSIX terminal
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
+You can also do this for most systems using the C<Term::ReadKey> module
from CPAN, which is easier to use and in theory more portable.
use Term::ReadKey;
If you expect to use both read and write operations on the device,
you'll have to open it for update (see L<perlfunc/"open"> for
details). You may wish to open it without running the risk of
-blocking by using sysopen() and C<O_RDWR|O_NDELAY|O_NOCTTY> from the
-Fcntl module (part of the standard perl distribution). See
+blocking by using C<sysopen()> and C<O_RDWR|O_NDELAY|O_NOCTTY> from the
+C<Fcntl> module (part of the standard perl distribution). See
L<perlfunc/"sysopen"> for more on this approach.
=item end of line
=item flushing output
-If you expect characters to get to your device when you print() them,
-you'll want to autoflush that filehandle. You can use select()
+If you expect characters to get to your device when you C<print()> them,
+you'll want to autoflush that filehandle. You can use C<select()>
and the C<$|> variable to control autoflushing (see L<perlvar/$E<verbar>>
and L<perlfunc/select>, or L<perlfaq5>, "How do I flush/unbuffer an
output filehandle? Why must I do this?"):
select((select(DEV), $| = 1)[0]);
Or if you don't mind pulling in a few thousand lines
-of code just because you're afraid of a little $| variable:
+of code just because you're afraid of a little C<$|> variable:
use IO::Handle;
DEV->autoflush(1);
=item non-blocking input
-If you are doing a blocking read() or sysread(), you'll have to
+If you are doing a blocking C<read()> or C<sysread()>, you'll have to
arrange for an alarm handler to provide a timeout (see
L<perlfunc/alarm>). If you have a non-blocking open, you'll likely
have a non-blocking read, which means you may have to use a 4-arg
-select() to determine whether I/O is ready on that device (see
+C<select()> to determine whether I/O is ready on that device (see
L<perlfunc/"select">.
=back
While trying to read from his caller-id box, the notorious Jamie Zawinski
-C<< <jwz@netscape.com> >>, after much gnashing of teeth and fighting with sysread,
-sysopen, POSIX's tcgetattr business, and various other functions that
+C<< <jwz@netscape.com> >>, after much gnashing of teeth and fighting with C<sysread>,
+C<sysopen>, POSIX's C<tcgetattr> business, and various other functions that
go bump in the night, finally came up with this:
sub open_modem {
tasks. Process management depends on your particular operating system,
and many of the techniques are in L<perlipc>.
-Several CPAN modules may be able to help, including IPC::Open2 or
-IPC::Open3, IPC::Run, Parallel::Jobs, Parallel::ForkManager, POE,
-Proc::Background, and Win32::Process. There are many other modules you
+Several CPAN modules may be able to help, including C<IPC::Open2> or
+C<IPC::Open3>, C<IPC::Run>, C<Parallel::Jobs>, C<Parallel::ForkManager>, C<POE>,
+C<Proc::Background>, and C<Win32::Process>. There are many other modules you
might use, so check those namespaces for other options too.
If you are on a unix-like system, you might be able to get away with a
$SIG{CHLD} = 'IGNORE';
-You can also use a double fork. You immediately wait() for your
-first child, and the init daemon will wait() for your grandchild once
+You can also use a double fork. You immediately C<wait()> for your
+first child, and the init daemon will C<wait()> for your grandchild once
it exits.
unless ($pid = fork) {
Signals are documented in L<perlipc/"Signals"> and the
section on "Signals" in the Camel.
-You can set the values of the %SIG hash to be the functions you want
-to handle the signal. After perl catches the signal, it looks in %SIG
+You can set the values of the C<%SIG> hash to be the functions you want
+to handle the signal. After perl catches the signal, it looks in C<%SIG>
for a key with the same name as the signal, then calls the subroutine
value for that key.
Perl versions before 5.8 had in its C source code signal handlers which
would catch the signal and possibly run a Perl function that you had set
-in %SIG. This violated the rules of signal handling at that level
-causing perl to dump core. Since version 5.8.0, perl looks at %SIG
-*after* the signal has been caught, rather than while it is being caught.
+in C<%SIG>. This violated the rules of signal handling at that level
+causing perl to dump core. Since version 5.8.0, perl looks at C<%SIG>
+B<after> the signal has been caught, rather than while it is being caught.
Previous versions of this answer were incorrect.
=head2 How do I modify the shadow password file on a Unix system?
If perl was installed correctly and your shadow library was written
-properly, the
getpw*() functions described in L<perlfunc> should in
+properly, the
C<getpw*()> functions described in L<perlfunc> should in
theory provide (read-only) access to entries in the shadow password
file. To change the file, make a new shadow password file (the format
varies from system to system--see L<passwd> for specifics) and use
-
pwd_mkdb(8) to install it (see L<pwd_mkdb> for more details).
+
C<pwd_mkdb(8)> to install it (see L<pwd_mkdb> for more details).
=head2 How do I set the time and date?
Assuming you're running under sufficient permissions, you should be
-able to set the system-wide date and time by running the date(1)
+able to set the system-wide date and time by running the C<date(1)>
program. (There is no way to set the time and date on a per-process
basis.) This mechanism will work for Unix, MS-DOS, Windows, and NT;
the VMS equivalent is C<set time>.
=head2 How can I do an atexit() or setjmp()/longjmp()? (Exception handling)
Release 5 of Perl added the END block, which can be used to simulate
-atexit(). Each package's END block is called when the program or
+C<atexit()>. Each package's END block is called when the program or
thread ends (see L<perlmod> manpage for more details).
For example, you can use this to make sure your filter program
close(STDOUT) || die "stdout close failed: $!";
}
-The END block isn't called when untrapped signals kill the program,
-though, so if you use END blocks you should also use
+The C<END> block isn't called when untrapped signals kill the program,
+though, so if you use C<END> blocks you should also use
use sigtrap qw(die normal-signals);
-Perl's exception-handling mechanism is its eval() operator. You can
-use eval() as setjmp and die() as longjmp. For details of this, see
+Perl's exception-handling mechanism is its C<eval()> operator. You can
+use C<eval()> as C<setjmp> and C<die()> as C<longjmp>. For details of this, see
the section on signals, especially the time-out handler for a blocking
-
flock() in L<perlipc/"Signals"> or the section on "Signals" in
+
C<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).
+C<exceptions.pl> library (part of the standard perl distribution).
If you want the atexit() syntax (and an rmexit() as well), try the
AtExit module available from CPAN.
In most cases, you write an external module to do it--see the answer
to "Where can I learn about linking C with Perl? [h2xs, xsubpp]".
However, if the function is a system call, and your system supports
-syscall(), you can use the syscall function (documented in
+C<syscall()>, you can use the C<syscall> function (documented in
L<perlfunc>).
Remember to check the modules that came with your distribution, and
CPAN as well--someone may already have written a module to do it. On
-Windows, try Win32::API. On Macs, try Mac::Carbon. If no module
+Windows, try C<Win32::API>. On Macs, try C<Mac::Carbon>. If no module
has an interface to the C function, you can inline a bit of C in your
-Perl source with Inline::C.
+Perl source with C<Inline::C>.
=head2 Where do I get the include files to do ioctl() or syscall()?
-Historically, these would be generated by the h2ph tool, part of the
-standard perl distribution. This program converts cpp(1) directives
+Historically, these would be generated by the C<h2ph> tool, part of the
+standard perl distribution. This program converts C<cpp(1)> directives
in C header files to files containing subroutine definitions, like
-&SYS_getitimer, which you can use as arguments to your functions.
+C<&SYS_getitimer>, which you can use as arguments to your functions.
It doesn't work perfectly, but it usually gets most of the job done.
Simple files like F<errno.h>, F<syscall.h>, and F<socket.h> were fine,
-but the hard ones like F<ioctl.h> nearly always need to hand-edited.
+but the hard ones like F<ioctl.h> nearly always need to be hand-edited.
Here's how to install the *.ph files:
1. become super-user
3. h2ph *.h */*.h
If your system supports dynamic loading, for reasons of portability and
-sanity you probably ought to use h2xs (also part of the standard perl
+sanity you probably ought to use C<h2xs> (also part of the standard perl
distribution). This tool converts C header files to Perl extensions.
-See L<perlxstut> for how to get started with h2xs.
+See L<perlxstut> for how to get started with C<h2xs>.
If your system doesn't support dynamic loading, you still probably
-ought to use
h2xs. See L<perlxstut> and L<ExtUtils::MakeMaker> for
+ought to use
C<h2xs>. See L<perlxstut> and L<ExtUtils::MakeMaker> for
more information (in brief, just use B<make perl> instead of a plain
B<make> to rebuild perl with a new static extension).
=head2 How can I open a pipe both to and from a command?
-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,
+The C<IPC::Open2> module (part of the standard perl distribution) is an
+easy-to-use approach that internally uses C<pipe()>, C<fork()>, and C<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">
-You may also use the IPC::Open3 module (part of the standard perl
+You may also use the C<IPC::Open3> module (part of the standard perl
distribution), but be warned that it has a different order of
-arguments from IPC::Open2 (see L<IPC::Open3>).
+arguments from C<IPC::Open2> (see L<IPC::Open3>).
=head2 Why can't I get the output of a command with system()?
-You're confusing the purpose of system() and backticks (``). system()
+You're confusing the purpose of C<system()> and backticks (``). C<system()>
runs a command and returns exit status information (as a 16 bit value:
the low 7 bits are the signal the process died from, if any, and
the high 8 bits are the actual exit value). Backticks (``) run a
$output = `$cmd`; # using backticks (``)
open (PIPE, "cmd |"); # using open()
-With system(), both STDOUT and STDERR will go the same place as the
-script's STDOUT and STDERR, unless the system() command redirects them.
-Backticks and open() read B<only> the STDOUT of your command.
+With C<system()>, both STDOUT and STDERR will go the same place as the
+script's STDOUT and STDERR, unless the C<system()> command redirects them.
+Backticks and C<open()> read B<only> the STDOUT of your command.
-You can also use the open3() function from IPC::Open3. Benjamin
+You can also use the C<open3()> function from C<IPC::Open3>. Benjamin
Goldberg provides some sample code:
To capture a program's STDOUT, but discard its STDERR:
while( <CATCHOUT> ) {}
while( <CATCHERR> ) {}
-But there's no real need for *both* to be tempfiles... the following
+But there's no real need for B<both> to be tempfiles... the following
should work just as well, without deadlocking:
use IPC::Open3;
open(STDERR, ">&STDOUT");
$alloutput = `cmd args`; # stderr still escapes
-This fails because the open() makes STDERR go to where STDOUT was
-going at the time of the open(). The backticks then make STDOUT go to
+This fails because the C<open()> makes STDERR go to where STDOUT was
+going at the time of the C<open()>. The backticks then make STDOUT go to
a string, but don't change STDERR (which still goes to the old
STDOUT).
-Note that you I<must> use Bourne shell (sh(1)) redirection syntax in
-backticks, not csh(1)! Details on why Perl's system() and backtick
+Note that you I<must> use Bourne shell (C<sh(1)>) redirection syntax in
+backticks, not C<csh(1)>! Details on why Perl's C<system()> and backtick
and pipe opens all use the Bourne shell are in the
F<versus/csh.whynot> article in the "Far More Than You Ever Wanted To
Know" collection in http://www.cpan.org/misc/olddoc/FMTEYEWTK.tgz . To
=head2 Why doesn't open() return an error when a pipe open fails?
-If the second argument to a piped open() contains shell
-metacharacters, perl fork()s, then exec()s a shell to decode the
+If the second argument to a piped C<open()> contains shell
+metacharacters, perl C<fork()>s, then C<exec()>s a shell to decode the
metacharacters and eventually run the desired program. If the program
couldn't be run, it's the shell that gets the message, not Perl. All
your Perl program can find out is whether the shell itself could be
successfully started. You can still capture the shell's STDERR and
check it for error messages. See L<"How can I capture STDERR from an
external command?"> elsewhere in this document, or use the
-IPC::Open3 module.
+C<IPC::Open3> module.
-If there are no shell metacharacters in the argument of open(), Perl
+If there are no shell metacharacters in the argument of C<open()>, Perl
runs the command directly, without using the shell, and can correctly
report whether the command started.
This happens only if your perl is compiled to use stdio instead of
perlio, which is the default. Some (maybe all?) stdio's set error and
-eof flags that you may need to clear. The POSIX module defines
-clearerr() that you can use. That is the technically correct way to
+eof flags that you may need to clear. The C<POSIX> module defines
+C<clearerr()> that you can use. That is the technically correct way to
do it. Here are some less reliable workarounds:
=over 4
=head2 Can I use perl to run a telnet or ftp session?
-Try the Net::FTP, TCP::Client, and Net::Telnet modules (available from
+Try the C<Net::FTP>, C<TCP::Client>, and C<Net::Telnet> modules (available from
CPAN). http://www.cpan.org/scripts/netstuff/telnet.emul.shar
-will also help for emulating the telnet protocol, but Net::Telnet is
-quite probably easier to use..
+will also help for emulating the telnet protocol, but C<Net::Telnet> is
+quite probably easier to use.
If all you want to do is pretend to be telnet but don't need
the initial telnet handshaking, then the standard dual-process
=head2 How can I write expect in Perl?
-Once upon a time, there was a library called chat2.pl (part of the
+Once upon a time, there was a library called L<chat2.pl> (part of the
standard perl distribution), which never really got finished. If you
find it somewhere, I<don't use it>. These days, your best bet is to
look at the Expect module available from CPAN, which also requires two
-other modules from CPAN, IO::Pty and IO::Stty.
+other modules from CPAN, C<IO::Pty> and C<IO::Stty>.
=head2 Is there a way to hide perl's command line from programs such as "ps"?
different process from the shell it was started from. Changes to a
process are not reflected in its parent--only in any children
created after the change. There is shell magic that may allow you to
-fake it by eval()ing the script's output in your shell; check out the
+fake it by C<eval()>ing the script's output in your shell; check out the
comp.unix.questions FAQ for details.
=back
=item *
Open /dev/tty and use the TIOCNOTTY ioctl on it. See L<tty>
-for details. Or better yet, you can just use the POSIX::setsid()
+for details. Or better yet, you can just use the C<POSIX::setsid()>
function, so you don't have to worry about process groups.
=item *
=back
-The Proc::Daemon module, available from CPAN, provides a function to
+The C<Proc::Daemon> module, available from CPAN, provides a function to
perform these actions for you.
=head2 How do I find out if I'm running interactively or not?
=head2 How do I timeout a slow event?
-Use the alarm() function, probably in conjunction with a signal
+Use the C<alarm()> function, probably in conjunction with a signal
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.
+C<Sys::AlarmCall> module available from CPAN.
-The alarm() function is not implemented on all versions of Windows.
+The C<alarm()> function is not implemented on all versions of Windows.
Check the documentation for your specific version of Perl.
=head2 How do I set CPU limits?
=head2 How do I avoid zombies on a Unix system?
-Use the reaper code from L<perlipc/"Signals"> to call wait() when a
+Use the reaper code from L<perlipc/"Signals"> to call C<wait()> when a
SIGCHLD is received, or else use the double-fork technique described
in L<perlfaq8/"How do I start a process in the background?">.
=head2 How do I use an SQL database?
-The DBI module provides an abstract interface to most database
+The C<DBI> module provides an abstract interface to most database
servers and types, including Oracle, DB2, Sybase, mysql, Postgresql,
ODBC, and flat files. The DBI module accesses each database type
through a database driver, or DBD. You can see a complete list of
available drivers on CPAN: http://www.cpan.org/modules/by-module/DBD/ .
You can read more about DBI on http://dbi.perl.org .
-Other modules provide more specific access: Win32::ODBC, Alzabo, iodbc,
+Other modules provide more specific access: C<Win32::ODBC>, C<Alzabo>, C<iodbc>,
and others found on CPAN Search: http://search.cpan.org .
=head2 How do I make a system() exit on control-C?
-You can't. You need to imitate the
system() call (see L<perlipc> for
+You can't. You need to imitate the
C<system()> call (see L<perlipc> for
sample code) and then have a signal handler for the INT signal that
passes the signal on to the subprocess. Or you can check for it:
If you're lucky enough to be using a system that supports
non-blocking reads (most Unixish systems do), you need only to use the
-O_NDELAY or O_NONBLOCK flag from the Fcntl module in conjunction with
-sysopen():
+C<O_NDELAY> or C<O_NONBLOCK> flag from the C<Fcntl> module in conjunction with
+C<sysopen()>:
use Fcntl;
sysopen(FH, "/foo/somefile", O_WRONLY|O_NDELAY|O_CREAT, 0644)
print "Hello World\n";
I get an error when I run this from my shell (which happens to be
-bash). That may look like perl forgot it has a print() function,
+bash). That may look like perl forgot it has a C<print()> function,
but my shebang line is not the path to perl, so the shell runs the
script, and I get the error.
$x / 0;
__END__
-The perl message comes out with "Perl" in front. The BEGIN block
+The perl message comes out with "Perl" in front. The C<BEGIN> block
works at compile time so all of the compilation errors and warnings
get the "Perl:" prefix too.
You could also just know all the perl errors, and although there are
some people who may know all of them, you probably don't. However, they
-all should be in the perldiag manpage. If you don't find the error in
+all should be in the L<perldiag> manpage. If you don't find the error in
there, it probably isn't a perl error.
Looking up every message is not the easiest way, so let perl to do it
perl Makefile.PL INSTALL_BASE=/mydir/perl
-You can set this in your CPAN.pm configuration so modules automatically install
+You can set this in your C<CPAN.pm> configuration so modules automatically install
in your private library directory when you use the CPAN.pm shell:
% cpan
perl Build.PL --install_base /mydir/perl
-You can configure CPAN.pm to automatically use this option too:
+You can configure C<CPAN.pm> to automatically use this option too:
% cpan
cpan> o conf mbuild_arg --install_base /mydir/perl
There is one caveat with INSTALL_BASE, though, since it acts
differently than the PREFIX and LIB settings that older versions of
-ExtUtils::MakeMaker advocated. INSTALL_BASE does not support
+C<ExtUtils::MakeMaker> advocated. INSTALL_BASE does not support
installing modules for multiple versions of Perl or different
architectures under the same directory. You should consider if you
really want that , and if you do, use the older PREFIX and LIB
-settings. See the ExtUtils::Makemaker documentation for more details.
+settings. See the C<ExtUtils::Makemaker> documentation for more details.
=head2 How do I add the directory my program lives in to the module/library search path?
=back
The last is particularly useful because it knows about machine
-dependent architectures. The lib.pm pragmatic module was first
+dependent architectures. The C<lib.pm> pragmatic module was first
included with the 5.002 release of Perl.
=head2 What is socket.ph and where do I get it?
It's a Perl 4 style file defining values for system networking
-constants. Sometimes it is built using h2ph when Perl is installed,
+constants. Sometimes it is built using C<h2ph> when Perl is installed,
but other times it is not. Modern programs C<use Socket;> instead.
=head1 REVISION
projects / platform / upstream / perl.git / commitdiff