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GETOPT(1)

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NAME    [Toc]    [Back]

       getopt - parse command options (enhanced)

SYNOPSIS    [Toc]    [Back]

       getopt optstring parameters

       getopt [options] [--] optstring parameters

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

DESCRIPTION    [Toc]    [Back]

       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 occurence 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  COM-
       PATIBILITY 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    [Toc]    [Back]

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

       -h, --help
	      Output a small usage guide and exit succesfully. 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 cummulative.  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
	      options  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 short-
	      opts 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  currently
 `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 status 0.

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

PARSING    [Toc]    [Back]

       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 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 EXAM-
       PLES).  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  (ie.  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    [Toc]    [Back]

       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 compati-
       ble  (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) implemetations 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 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 occurences of `-' and `+' are ignored).

QUOTING    [Toc]    [Back]

       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 cshlike
 quoting conventions. Chances are that if  you  use	another  shell
       script language, one of these flavors can still be used.

SCANNING MODES    [Toc]    [Back]

       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 outputed  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    [Toc]    [Back]

       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  outputed  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_CORRECT
       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    [Toc]    [Back]

       getopt  returns	error  code  0	for  succesful 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    [Toc]    [Back]

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

ENVIRONMENT    [Toc]    [Back]

       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    [Toc]    [Back]

       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 explicitely to the empty string).

AUTHOR    [Toc]    [Back]

       Frodo Looijaard <frodol@dds.nl>

SEE ALSO    [Toc]    [Back]

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




Linux				 May 31, 1997			     GETOPT(1)
[ Back ]
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