getopt - parse command options (enhanced)


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


   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.


   -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


   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

   It  is possible to specify several short options after one '-', as long
   as all (except possibly the last) do  not  have  required  or  optional

   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


   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

   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).


   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.


   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.


   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

   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.


   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


   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.


          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 '-'.

          Forces getopt to use the first calling format  as  specified  in
          the SYNOPSIS.


   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).


   Frodo Looijaard


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


   The  getopt  command is part of the util-linux package and is available
   from Linux Kernel  Archive


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