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  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
       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/⟩.