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 com-
       patible	with  that  of	other versions of getopt(1).  It will still do
       parameter shuffling and recognize optional arguments (see section  COM-
       PATIBILITY for more information).

       Traditional implementations of getopt(1) are unable to cope with white-
       space 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 pre-
       serving 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 out-
	      put 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 followed 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 argu-
	      ment, 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  ver-
	      sion.  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 status 0.

       -V, --version
	      Output version information and exit successfully.	 No other out-
	      put 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  (OUTPUT)
       describes  the  output  that is generated.  These parameters were typi-
       cally the parameters a shell function was called with.	Care  must  be
       taken  that  each  parameter  the shell function was called with corre-
       sponds 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 clas-
       sified 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 white-
       space 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  abbreviated,
       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	 parameter  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 compat-
       ible (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 languages).   This  is
       imperfect  in  unquoted	mode,  as  elements can be split at unexpected
       places if they contain whitespace or special characters.

       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  parameter
       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 abbreviated
       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	gener-
       ated  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	gener-
       ated with quotes around each parameter.	When this output is once again
       fed to the shell (usually by a shell eval command), it  is  split  cor-
       rectly 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
       parameter  (ie.	 a  parameter that does not start with a '-') is found
       that is not an option  argument.	  The  remaining  parameters  are  all
       interpreted 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  col-
       lected  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  version
       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  compati-
       bility  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 parame-
	      ters 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)