GETOPT(1)							   User Commands							 GETOPT(1)

NAME

       getopt - parse command options (enhanced)

SYNOPSIS

       getopt optstring parameters
       getopt [options] [--] optstring parameters
       getopt [options] -o|--options optstring [options] [--] parameters

DESCRIPTION

       getopt  is used to break up (parse) options in command lines for easy parsing by shell procedures, and to check for legal options.  It uses
       the GNU getopt(3) routines to do this.

       The parameters getopt is called with can be divided into  two  parts:  options  which  modify  the  way	getopt	will  parse  (options  and
       -o|--options  optstring	in  the  SYNOPSIS),  and the parameters which are to be parsed (parameters in the SYNOPSIS).  The second part will
       start at the first non-option parameter that is not an option argument, or after the first occurrence of '--'.  If no '-o'  or  '--options'
       option is found in the first part, the first parameter of the second part is used as the short options string.

       If  the	environment  variable GETOPT_COMPATIBLE is set, or if its first parameter is not an option (does not start with a '-', this is the
       first format in the SYNOPSIS), getopt will generate output that is compatible with that of other versions of getopt(1).	It will  still	do
       parameter shuffling and recognize optional arguments (see section COMPATIBILITY for more information).

       Traditional  implementations of getopt(1) are unable to cope with whitespace and other (shell-specific) special characters in arguments and
       non-option parameters.  To solve this problem, this implementation can generate quoted output which must once again be interpreted  by  the
       shell  (usually	by using the eval command).  This has the effect of preserving those characters, but you must call getopt in a way that is
       no longer compatible with other versions (the second or third format in the SYNOPSIS).  To  determine  whether  this  enhanced  version	of
       getopt(1) is installed, a special test option (-T) can be used.

OPTIONS

       -a, --alternative
	      Allow long options to start with a single '-'.

       -h, --help
	      Output a small usage guide and exit successfully.  No other output is generated.

       -l, --longoptions longopts
	      The  long  (multi-character)  options to be recognized.  More than one option name may be specified at once, by separating the names
	      with commas.  This option may be given more than once, the longopts are cumulative.  Each long option name in longopts may  be  fol-
	      lowed by one colon to indicate it has a required argument, and by two colons to indicate it has an optional argument.

       -n, --name progname
	      The  name  that  will be used by the getopt(3) routines when it reports errors.  Note that errors of getopt(1) are still reported as
	      coming from getopt.

       -o, --options shortopts
	      The short (one-character) options to be recognized.  If this option is not found, the first parameter of getopt that does not  start
	      with  a  '-'  (and  is not an option argument) is used as the short options string.  Each short option character in shortopts may be
	      followed by one colon to indicate it has a required argument, and by two colons to indicate it has an optional argument.	The  first
	      character of shortopts may be '+' or '-' to influence the way options are parsed and output is generated (see section SCANNING MODES
	      for details).

       -q, --quiet
	      Disable error reporting by getopt(3).

       -Q, --quiet-output
	      Do not generate normal output.  Errors are still reported by getopt(3), unless you also use -q.

       -s, --shell shell
	      Set quoting conventions to those of shell.  If no -s argument is found, the BASH conventions are used.   Valid  arguments  are  cur-
	      rently 'sh' 'bash', 'csh', and 'tcsh'.

       -u, --unquoted
	      Do  not  quote the output.  Note that whitespace and special (shell-dependent) characters can cause havoc in this mode (like they do
	      with other getopt(1) implementations).

       -T, --test
	      Test if your getopt(1) is this enhanced version or an old version.  This generates no output, and sets the error status to 4.  Other
	      implementations of getopt(1), and this version if the environment variable GETOPT_COMPATIBLE is set, will return '--' and error sta-
	      tus 0.

       -V, --version
	      Output version information and exit successfully.  No other output is generated.

PARSING

       This section specifies the format of the second part of the parameters of getopt (the parameters in the SYNOPSIS).  The next section  (OUT-
       PUT)  describes	the output that is generated.  These parameters were typically the parameters a shell function was called with.  Care must
       be taken that each parameter the shell function was called with corresponds to exactly one parameter in the parameter list of  getopt  (see
       the EXAMPLES).  All parsing is done by the GNU getopt(3) routines.

       The  parameters are parsed from left to right.  Each parameter is classified as a short option, a long option, an argument to an option, or
       a non-option parameter.

       A simple short option is a '-' followed by a short option character.  If the option has a required argument, it	may  be  written  directly
       after  the  option  character  or  as the next parameter (ie.  separated by whitespace on the command line).  If the option has an optional
       argument, it must be written directly after the option character if present.

       It is possible to specify several short options after one '-', as long as all (except possibly the last) do not have required  or  optional
       arguments.

       A  long	option	normally  begins  with	'--'  followed	by the long option name.  If the option has a required argument, it may be written
       directly after the long option name, separated by '=', or as the next argument (i.e. separated by whitespace on the command line).  If  the
       option  has  an optional argument, it must be written directly after the long option name, separated by '=', if present (if you add the '='
       but nothing behind it, it is interpreted as if no argument was present; this is a slight bug, see the BUGS).  Long options may be  abbrevi-
       ated, as long as the abbreviation is not ambiguous.

       Each  parameter not starting with a '-', and not a required argument of a previous option, is a non-option parameter.  Each parameter after
       a '--' parameter is always interpreted as a non-option parameter.  If the environment variable POSIXLY_CORRECT is  set,	or  if	the  short
       option string started with a '+', all remaining parameters are interpreted as non-option parameters as soon as the first non-option parame-
       ter is found.

OUTPUT

       Output is generated for each element described in the previous section.	Output is done in the same order as the elements are specified	in
       the  input,  except  for non-option parameters.	Output can be done in compatible (unquoted) mode, or in such way that whitespace and other
       special characters within arguments and non-option parameters are preserved (see QUOTING).  When the  output  is  processed  in	the  shell
       script,	it  will  seem to be composed of distinct elements that can be processed one by one (by using the shift command in most shell lan-
       guages).  This is imperfect in unquoted mode, as elements can be split at unexpected places if they contain whitespace or  special  charac-
       ters.

       If there are problems parsing the parameters, for example because a required argument is not found or an option is not recognized, an error
       will be reported on stderr, there will be no output for the offending element, and a non-zero error status is returned.

       For a short option, a single '-' and the option character are generated as one parameter.  If the option has an argument, the next  parame-
       ter  will be the argument.  If the option takes an optional argument, but none was found, the next parameter will be generated but be empty
       in quoting mode, but no second parameter will be generated in unquoted (compatible) mode.  Note that many other	getopt(1)  implementations
       do not support optional arguments.

       If several short options were specified after a single '-', each will be present in the output as a separate parameter.

       For  a  long option, '--' and the full option name are generated as one parameter.  This is done regardless whether the option was abbrevi-
       ated or specified with a single '-' in the input.  Arguments are handled as with short options.

       Normally, no non-option parameters output is generated until all options and their arguments have been generated.  Then '--'  is  generated
       as  a  single  parameter,  and  after it the non-option parameters in the order they were found, each as a separate parameter.  Only if the
       first character of the short options string was a '-', non-option parameter output is generated at the place they are found  in	the  input
       (this is not supported if the first format of the SYNOPSIS is used; in that case all preceding occurrences of '-' and '+' are ignored).

QUOTING

       In  compatible  mode, whitespace or 'special' characters in arguments or non-option parameters are not handled correctly.  As the output is
       fed to the shell script, the script does not know how it is supposed to break the output into  separate	parameters.   To  circumvent  this
       problem,  this implementation offers quoting.  The idea is that output is generated with quotes around each parameter.  When this output is
       once again fed to the shell (usually by a shell eval command), it is split correctly into separate parameters.

       Quoting is not enabled if the environment variable GETOPT_COMPATIBLE is set, if the first form of the SYNOPSIS is used, or  if  the  option
       '-u' is found.

       Different  shells  use different quoting conventions.  You can use the '-s' option to select the shell you are using.  The following shells
       are currently supported: 'sh', 'bash', 'csh' and 'tcsh'.  Actually, only two 'flavors' are distinguished: sh-like quoting  conventions  and
       csh-like quoting conventions.  Chances are that if you use another shell script language, one of these flavors can still be used.

SCANNING MODES

       The  first  character  of the short options string may be a '-' or a '+' to indicate a special scanning mode.  If the first calling form in
       the SYNOPSIS is used they are ignored; the environment variable POSIXLY_CORRECT is still examined, though.

       If the first character is '+', or if the environment variable POSIXLY_CORRECT is set, parsing stops as soon as the first non-option parame-
       ter  (ie.   a  parameter  that does not start with a '-') is found that is not an option argument.  The remaining parameters are all inter-
       preted as non-option parameters.

       If the first character is a '-', non-option parameters are outputted at the place where they are found; in normal operation, they  are  all
       collected  at  the  end of output after a '--' parameter has been generated.  Note that this '--' parameter is still generated, but it will
       always be the last parameter in this mode.

COMPATIBILITY

       This version of getopt(1) is written to be as compatible as possible to other versions.	Usually you can just replace them with	this  ver-
       sion without any modifications, and with some advantages.

       If  the	first  character  of the first parameter of getopt is not a '-', getopt goes into compatibility mode.  It will interpret its first
       parameter as the string of short options, and all other arguments will  be  parsed.   It  will  still  do  parameter  shuffling	(ie.   all
       non-option parameters are outputted at the end), unless the environment variable POSIXLY_CORRECT is set.

       The  environment variable GETOPT_COMPATIBLE forces getopt into compatibility mode.  Setting both this environment variable and POSIXLY_COR-
       RECT offers 100% compatibility for 'difficult' programs.  Usually, though, neither is needed.

       In compatibility mode, leading '-' and '+' characters in the short options string are ignored.

RETURN CODES

       getopt returns error code 0 for successful parsing, 1 if getopt(3) returns errors, 2 if it does not understand its own parameters, 3 if	an
       internal error occurs like out-of-memory, and 4 if it is called with -T.

EXAMPLES

       Example	scripts  for (ba)sh and (t)csh are provided with the getopt(1) distribution, and are optionally installed in /usr/share/getopt/ or
       /usr/share/docs/ in util-linux subdirectory.

ENVIRONMENT

       POSIXLY_CORRECT
	      This environment variable is examined by the getopt(3) routines.	If it is set, parsing stops as soon as a parameter is  found  that
	      is  not an option or an option argument.	All remaining parameters are also interpreted as non-option parameters, regardless whether
	      they start with a '-'.

       GETOPT_COMPATIBLE
	      Forces getopt to use the first calling format as specified in the SYNOPSIS.

BUGS

       getopt(3) can parse long options with optional arguments that are given an empty optional argument (but can not do this for short options).
       This getopt(1) treats optional arguments that are empty as if they were not present.

       The  syntax  if	you  do  not  want  any  short option variables at all is not very intuitive (you have to set them explicitly to the empty
       string).

AUTHOR

       Frodo Looijaard <frodo@frodo.looijaard.name>

SEE ALSO

       getopt(3), bash(1), tcsh(1).

AVAILABILITY

       The getopt command is part of the util-linux package and is available from Linux Kernel Archive <ftp://ftp.kernel.org/pub/linux/utils/util-
       linux/>.

util-linux							     June 2012								 GETOPT(1)