FileCache(3perl) Perl Programmers Reference Guide FileCache(3perl)
NAME
FileCache - keep more files open than the system permits
SYNOPSIS
no strict 'refs';
use FileCache;
# or
use FileCache maxopen => 16;
cacheout $mode, $path;
# or
cacheout $path;
print $path @data;
$fh = cacheout $mode, $path;
# or
$fh = cacheout $path;
print $fh @data;
DESCRIPTION
The "cacheout" function will make sure that there's a filehandle open
for reading or writing available as the pathname you give it. It
automatically closes and re-opens files if you exceed your system's
maximum number of file descriptors, or the suggested maximum maxopen.
cacheout EXPR
The 1-argument form of cacheout will open a file for writing ('>')
on it's first use, and appending ('>>') thereafter.
Returns EXPR on success for convenience. You may neglect the return
value and manipulate EXPR as the filehandle directly if you prefer.
cacheout MODE, EXPR
The 2-argument form of cacheout will use the supplied mode for the
initial and subsequent openings. Most valid modes for 3-argument
"open" are supported namely; '>', '+>', '<', '<+', '>>', '|-' and
'-|'
To pass supplemental arguments to a program opened with '|-' or
'-|' append them to the command string as you would system EXPR.
Returns EXPR on success for convenience. You may neglect the return
value and manipulate EXPR as the filehandle directly if you prefer.
CAVEATS
While it is permissible to "close" a FileCache managed file, do not do
so if you are calling "FileCache::cacheout" from a package other than
which it was imported, or with another module which overrides "close".
If you must, use "FileCache::cacheout_close".
Although FileCache can be used with piped opens ('-|' or '|-') doing so
is strongly discouraged. If FileCache finds it necessary to close and
then reopen a pipe, the command at the far end of the pipe will be
reexecuted - the results of performing IO on FileCache'd pipes is
unlikely to be what you expect. The ability to use FileCache on pipes
may be removed in a future release.
FileCache does not store the current file offset if it finds it
necessary to close a file. When the file is reopened, the offset will
be as specified by the original "open" file mode. This could be
construed to be a bug.
The module functionality relies on symbolic references, so things will
break under 'use strict' unless 'no strict "refs"' is also specified.
BUGS
sys/param.h lies with its "NOFILE" define on some systems, so you may
have to set maxopen yourself.
perl v5.40.1 2026-08-30 FileCache(3perl)
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