getopt(1)



GETOPT(1)                        User Commands                       GETOPT(1)

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: op-
       tions 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 shuf-
       fling and recognize optional arguments (see section  COMPATIBILITY  for
       more information).

       Traditional implementations of getopt(1) are unable to cope with white-
       space 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 pre-
       serving 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 re-
              ports  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 op-
              tion  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 argu-
              ment, 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 ver-
              sion.  This generates no output, and sets the error status to 4.
              Other  implementations of getopt(1), and this version if the en-
              vironment 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 gener-
              ated.

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  typi-
       cally  the  parameters  a shell function was called with.  Care must be
       taken that each parameter the shell function  was  called  with  corre-
       sponds  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  clas-
       sified 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 argu-
       ment, 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  ar-
       guments.

       A  long  option  normally  begins with '--' followed by the long option
       name.  If the option has a required argument, it  may  be  written  di-
       rectly after the long option name, separated by '=', or as the next ar-
       gument (i.e., separated by whitespace on the command line).  If the op-
       tion  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 compat-
       ible (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 re-
       quired  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 op-
       tions 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  gener-
       ated with quotes around each parameter.  When this output is once again
       fed to the shell (usually by a shell eval command), it  is  split  cor-
       rectly 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  in-
       terpreted 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  col-
       lected  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  pa-
       rameter as the string of short options, and all other arguments will be
       parsed.  It will still do parameter shuffling (i.e., all non-option pa-
       rameters  are  output  at  the  end),  unless  the environment variable
       POSIXLY_CORRECT is set.

       The environment variable GETOPT_COMPATIBLE forces getopt into  compati-
       bility  mode.   Setting both this environment variable and POSIXLY_COR-
       RECT offers 100%  compatibility  for  'difficult'  programs.   Usually,
       though, neither is needed.

       In  compatibility mode, leading '-' and '+' characters in the short op-
       tions string are ignored.

RETURN CODES
       getopt returns error code 0 for successful parsing, 1 if getopt(3)  re-
       turns  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 parame-
              ters 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/>.

util-linux                       December 2014                       GETOPT(1)

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