X-Git-Url: https://perl5.git.perl.org/perl5.git/blobdiff_plain/2359510ddb135dcc6e80153f51cff0a97b20b597..740d4bb23b722729f87a23733be98429529fd900:/pod/perlopentut.pod diff --git a/pod/perlopentut.pod b/pod/perlopentut.pod index 0b60096..18bc369 100644 --- a/pod/perlopentut.pod +++ b/pod/perlopentut.pod @@ -67,7 +67,7 @@ examples would effectively mean which is definitely not what you want. The other important thing to notice is that, just as in the shell, -any white space before or after the filename is ignored. This is good, +any whitespace before or after the filename is ignored. This is good, because you wouldn't want these to do different things: open INFO, " mimics the shell in its style of using redirection arrows to specify how to open the file, it -also does so with respect to extra white space around the filename itself +also does so with respect to extra whitespace around the filename itself as well. For accessing files with naughty names, see L<"Dispelling the Dweomer">. @@ -195,7 +195,7 @@ whether it only works on existing files or always clobbers existing ones. open(SCREEN, "+> lkscreen") || die "can't open lkscreen: $!"; - open(LOGFILE, "+>> /var/log/applog" + open(LOGFILE, "+>> /var/log/applog") || die "can't open /var/log/applog: $!"; The first one won't create a new file, and the second one will always @@ -230,7 +230,7 @@ on each file in @ARGV. Thus a program called like this: $ myprogram file1 file2 file3 -Can have all its files opened and processed one at a time +can have all its files opened and processed one at a time using a construct no more complex than: while (<>) { @@ -332,7 +332,7 @@ C takes 3 (or 4) arguments. The HANDLE argument is a filehandle just as with C. The PATH is a literal path, one that doesn't pay attention to any greater-thans or -less-thans or pipes or minuses, nor ignore white space. If it's there, +less-thans or pipes or minuses, nor ignore whitespace. If it's there, it's part of the path. The FLAGS argument contains one or more values derived from the Fcntl module that have been or'd together using the bitwise "|" operator. The final argument, the MASK, is optional; if @@ -364,7 +364,7 @@ added to the sysopen() flags because large files are the default.) Here's how to use C to emulate the simple C calls we had before. We'll omit the C<|| die $!> checks for clarity, but make sure you always check the return values in real code. These aren't quite -the same, since C will trim leading and trailing white space, +the same, since C will trim leading and trailing whitespace, but you'll get the idea. To open a file for reading: @@ -487,7 +487,7 @@ If the filehandle or descriptor number is preceded not just with a simple "&" but rather with a "&=" combination, then Perl will not create a completely new descriptor opened to the same place using the dup(2) system call. Instead, it will just make something of an alias to the -existing one using the fdopen(3S) library call This is slightly more +existing one using the fdopen(3S) library call. This is slightly more parsimonious of systems resources, although this is less a concern these days. Here's an example of that: @@ -521,7 +521,7 @@ working directory, slash the directory separator, and disallows ASCII NULs within a valid filename. Most systems follow these conventions, including all POSIX systems as well as proprietary Microsoft systems. The only vaguely popular system that doesn't work this way is the -proprietary Macintosh system, which uses a colon where the rest of us +"Classic" Macintosh system, which uses a colon where the rest of us use a slash. Maybe C isn't such a bad idea after all. If you want to use C<< >> processing in a totally boring @@ -723,7 +723,9 @@ With descriptors that you haven't opened using C, such as sockets, you can set them to be non-blocking using C: use Fcntl; - fcntl(Connection, F_SETFL, O_NONBLOCK) + my $old_flags = fcntl($handle, F_GETFL, 0) + or die "can't get flags: $!"; + fcntl($handle, F_SETFL, $old_flags | O_NONBLOCK) or die "can't set non blocking: $!"; Rather than losing yourself in a morass of twisting, turning Cs, @@ -915,7 +917,7 @@ second argument contains something else in addition to the usual C<< '<' >>, C<< '>' >>, C<< '>>' >>, C<< '|' >> and their variants, for example: - open(my $fh, "<:utf8", $fn); + open(my $fh, "<:crlf", $fn); =item *