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Full Discussion: File Descriptor Help
Top Forums UNIX for Dummies Questions & Answers File Descriptor Help Post 56892 by google on Thursday 14th of October 2004 05:08:00 AM
Old 10-14-2004
If you are familiar with UNIX I/O redirection, syntax similar to the following should not be new to you:
command > file 2>&1
When command runs it sends "normal" output to file, and any error messages generated by command are also written to file. "2>&1" handles the latter.

The 2 and 1 are file descriptors. So what's a file descriptor?

When a UNIX program wants to use a file, it must first open that file. When it does so, UNIX will associate a number with the file. This number, which is used by the program when reading from and writing to the file, is the file descriptor.

A typical UNIX program will open three files when it starts. These files are:

- standard input (also known as stdin)
- standard output (also known as stdout)
- standard error (also known as stderr)

Standard input has a file descriptor of 0, standard output uses 1, and the number 2 is used by standard error.
 

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LEARN ABOUT CENTOS

file::spec::cygwin

File::Spec::Cygwin(3)					User Contributed Perl Documentation				     File::Spec::Cygwin(3)

NAME

       File::Spec::Cygwin - methods for Cygwin file specs

SYNOPSIS

	require File::Spec::Cygwin; # Done internally by File::Spec if needed

DESCRIPTION

       See File::Spec and File::Spec::Unix.  This package overrides the implementation of these methods, not the semantics.

       This module is still in beta.  Cygwin-knowledgeable folks are invited to offer patches and suggestions.

       canonpath
	   Any "" (backslashes) are converted to "/" (forward slashes), and then File::Spec::Unix canonpath() is called on the result.

       file_name_is_absolute
	   True is returned if the file name begins with "drive_letter:", and if not, File::Spec::Unix file_name_is_absolute() is called.

       tmpdir (override)
	   Returns a string representation of the first existing directory from the following list:

	       $ENV{TMPDIR}
	       /tmp
	       $ENV{'TMP'}
	       $ENV{'TEMP'}
	       C:/temp

	   Since Perl 5.8.0, if running under taint mode, and if the environment variables are tainted, they are not used.

       case_tolerant
	   Override Unix. Cygwin case-tolerance depends on managed mount settings and as with MsWin32 on GetVolumeInformation() $ouFsFlags ==
	   FS_CASE_SENSITIVE, indicating the case significance when comparing file specifications.  Default: 1

COPYRIGHT

       Copyright (c) 2004,2007 by the Perl 5 Porters.  All rights reserved.

       This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

perl v5.16.3							    2013-01-16						     File::Spec::Cygwin(3)
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