File: coreutils.info,  Node: Common options,  Next: Output of entire files,  Prev: Introduction,  Up: Top

2 Common options
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Certain options are available in all of these programs.  Rather than
writing identical descriptions for each of the programs, they are
described here.  (In fact, every GNU program accepts (or should accept)
these options.)

   Normally options and operands can appear in any order, and programs
act as if all the options appear before any operands.  For example,
‘sort -r passwd -t :’ acts like ‘sort -r -t : passwd’, since ‘:’ is an
option-argument of ‘-t’.  However, if the ‘POSIXLY_CORRECT’ environment
variable is set, options must appear before operands, unless otherwise
specified for a particular command.

   A few programs can usefully have trailing operands with leading ‘-’.
With such a program, options must precede operands even if
‘POSIXLY_CORRECT’ is not set, and this fact is noted in the program
description.  For example, the ‘env’ command’s options must appear
before its operands, since in some cases the operands specify a command
that itself contains options.

   Most programs that accept long options recognize unambiguous
abbreviations of those options.  For example, ‘rmdir
--ignore-fail-on-non-empty’ can be invoked as ‘rmdir --ignore-fail’ or
even ‘rmdir --i’.  Ambiguous options, such as ‘ls --h’, are identified
as such.

   Some of these programs recognize the ‘--help’ and ‘--version’ options
only when one of them is the sole command line argument.  For these
programs, abbreviations of the long options are not always recognized.

‘--help’
     Print a usage message listing all available options, then exit
     successfully.

‘--version’
     Print the version number, then exit successfully.

‘--’
     Delimit the option list.  Later arguments, if any, are treated as
     operands even if they begin with ‘-’.  For example, ‘sort -- -r’
     reads from the file named ‘-r’.

   A single ‘-’ operand is not really an option, though it looks like
one.  It stands for a file operand, and some tools treat it as standard
input, or as standard output if that is clear from the context.  For
example, ‘sort -’ reads from standard input, and is equivalent to plain
‘sort’.  Unless otherwise specified, a ‘-’ can appear as any operand
that requires a file name.

* Menu:

Items shared between some programs:

* Backup options::               ‘-b’ ‘-S’.
* Block size::                   BLOCK_SIZE and ‘--block-size’.
* Signal specifications::        Specifying signals with ‘--signal’.
* Disambiguating names and IDs:: chgrp, chown, chroot, id: user and group syntax
* Random sources::               ‘--random-source’.
* Target directory::             Specifying a target directory.
* Trailing slashes::             ‘--strip-trailing-slashes’.
* Traversing symlinks::          ‘-H’, ‘-L’, or ‘-P’.
* Treating / specially::         ‘--preserve-root’ and the converse.
* Special built-in utilities::   ‘break’, ‘:’, ...

Items applicable to all programs:

* Exit status::                  Indicating program success or failure.
* Floating point::               Floating point number representation.
* Standards conformance::        Conformance to the POSIX standard.
* Multi-call invocation::        Multi-call program invocation.