Provided by: util-linux_2.34-0.1ubuntu2_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 valid 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 do the parsing (the options and the 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 the first parameter is not  an
       option (does not start with a '-', 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
              Display help text and exit.  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 the -s option is not given, the BASH
              conventions are used.  Valid  arguments  are  currently  'sh'  'bash',  'csh',  and
              'tcsh'.

       -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.

       -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).

       -V, --version
              Display version information and exit.  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 (i.e., 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 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 (i.e., 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 (i.e., all
       non-option  parameters  are  output  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/getopt/  or  /usr/share/doc/  in the 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 cannot 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

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

AVAILABILITY

       The getopt command is part of the util-linux package and is available  from  Linux  Kernel
       Archive ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩.