Provided by: util-linux_2.20.1-1ubuntu3_amd64 bug

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 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 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 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  (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 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 (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

       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 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 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 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 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 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 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

       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/doc/util-linux/examples.

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
       ftp://ftp.kernel.org/pub/linux/utils/util-linux/.