diff options
| -rw-r--r-- | pod/perlfunc.pod | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/pod/perlfunc.pod b/pod/perlfunc.pod index 088f1dd509..3497ca9bdf 100644 --- a/pod/perlfunc.pod +++ b/pod/perlfunc.pod @@ -2602,6 +2602,12 @@ parsimonious of file descriptors. For example: open(FILEHANDLE, "<&=$fd") +Note that this feature depends on the fdopen() C library function. +On many UNIX systems, fdopen() is known to fail when file descriptors +exceed a certain value, typically 255. If you need more file +descriptors than that, consider rebuilding Perl to use the C<sfio> +library. + If you open a pipe on the command C<'-'>, i.e., either C<'|-'> or C<'-|'> with 2-arguments (or 1-argument) form of open(), then there is an implicit fork done, and the return value of open is the pid @@ -4528,8 +4534,7 @@ For historical reasons, some values work on almost every system supported by perl: zero means read-only, one means write-only, and two means read/write. We know that these values do I<not> work under OS/390 & VM/ESA Unix and on the Macintosh; you probably don't want to -se them in new code, use thhe constants discussed in the preceding -paragraph. +use them in new code. If the file named by FILENAME does not exist and the C<open> call creates it (typically because MODE includes the C<O_CREAT> flag), then the value of @@ -4550,6 +4555,12 @@ that takes away the user's option to have a more permissive umask. Better to omit it. See the perlfunc(1) entry on C<umask> for more on this. +Note that C<sysopen> depends on the fdopen() C library function. +On many UNIX systems, fdopen() is known to fail when file descriptors +exceed a certain value, typically 255. If you need more file +descriptors than that, consider rebuilding Perl to use the C<sfio> +library, or perhaps using the POSIX::open() function. + See L<perlopentut> for a kinder, gentler explanation of opening files. =item sysread FILEHANDLE,SCALAR,LENGTH,OFFSET |