GETOPTS(1) User Commands GETOPTS(1)


NAME


getopts - parse utility options

SYNOPSIS


/usr/bin/getopts optstring name [arg...]


sh
getopts optstring name [argument]...


ksh
getopts optstring name [arg]...


ksh93
getopts [-a name] optstring name [arg]...


DESCRIPTION


/usr/bin/getopts
The getopts utility can be used to retrieve options and option-arguments
from a list of parameters.


Each time it is invoked, the getopts utility places the value of the next
option in the shell variable specified by the name operand and the index
of the next argument to be processed in the shell variable OPTIND.
Whenever the shell is invoked, OPTIND is initialized to 1.


When the option requires an option-argument, the getopts utility places
it in the shell variable OPTARG. If no option was found, or if the option
that was found does not have an option-argument, OPTARG is unset.


If an option character not contained in the optstring operand is found
where an option character is expected, the shell variable specified by
name is set to the question-mark ( ? ) character. In this case, if the
first character in optstring is a colon (:, the shell variable OPTARG is
set to the option character found, but no output is written to standard
error; otherwise, the shell variable OPTARG is unset and a diagnostic
message is written to standard error. This condition is considered to be
an error detected in the way arguments were presented to the invoking
application, but is not an error in getopts processing.


If an option-argument is missing:

o If the first character of optstring is a colon, the shell
variable specified by name is set to the colon character and
the shell variable OPTARG is set to the option character
found.

o Otherwise, the shell variable specified by name is set to the
question-mark character (?), the shell variable OPTARG is
unset, and a diagnostic message is written to standard error.
This condition is considered to be an error detected in the
way arguments were presented to the invoking application, but
is not an error in getopts processing; a diagnostic message is
written as stated, but the exit status is zero.


When the end of options is encountered, the getopts utility exits with a
return value greater than zero; the shell variable OPTIND is set to the
index of the first non-option-argument, where the first -- argument is
considered to be an option-argument if there are no other non-option-
arguments appearing before it, or the value $# + 1 if there are no non-
option-arguments; the name variable is set to the question-mark
character. Any of the following identifies the end of options: the
special option --, finding an argument that does not begin with a -, or
encountering an error.


The shell variables OPTIND and OPTARG are local to the caller of getopts
and are not exported by default.


The shell variable specified by the name operand, OPTIND and OPTARG
affect the current shell execution environment.


If the application sets OPTIND to the value 1, a new set of parameters
can be used: either the current positional parameters or new arg values.
Any other attempt to invoke getopts multiple times in a single shell
execution environment with parameters (positional parameters or arg
operands) that are not the same in all invocations, or with an OPTIND
value modified to be a value other than 1, produces unspecified results.

sh
getopts is a built-in Bourne shell command used to parse positional
parameters and to check for valid options. See sh(1). It supports all
applicable rules of the command syntax standard (see Rules 3-10,
Intro(1)). It should be used in place of the getopt command.


optstring must contain the option letters the command using getopts
recognizes. If a letter is followed by a colon, the option is expected to
have an argument, or group of arguments, which must be separated from it
by white space.


Each time it is invoked, getopts places the next option in the shell
variable name and the index of the next argument to be processed in the
shell variable OPTIND. Whenever the shell or a shell script is invoked,
OPTIND is initialized to 1.


When an option requires an option-argument, getopts places it in the
shell variable OPTARG.


If an illegal option is encountered, ? is placed in name.


When the end of options is encountered, getopts exits with a non-zero
exit status. The special option - can be used to delimit the end of the
options.


By default, getopts parses the positional parameters. If extra arguments
(argument ...) are specified on the getopts command line, getopts parses
them instead.


/usr/lib/getoptcvt reads the shell script in filename, converts it to use
getopts instead of getopt, and writes the results on the standard output.


So that all new commands adhere to the command syntax standard described
in Intro(1), they should use getopts or getopt to parse positional
parameters and check for options that are valid for that command.


getopts prints an error message on the standard error when it encounters
an option letter not included in optstring.


Although the following command syntax rule (see Intro(1)) relaxations are
permitted under the current implementation, they should not be used
because they can not be supported in future releases of the system. As in
the EXAMPLES section below, -a and -b are options, and the option -o
requires an option-argument.


The following example violates Rule 5: options with option-arguments must
not be grouped with other options:

example% cmd -aboxxx filename


The following example violates Rule 6: there must be white space after an
option that takes an option-argument:

example% cmd -ab oxxx filename


Changing the value of the shell variable OPTIND or parsing different sets
of arguments can lead to unexpected results.

ksh
Checks arg for legal options. If arg is omitted, the positional
parameters are used. An option argument begins with a + or a -. An option
not beginning with + or - or the argument - ends the options. optstring
contains the letters that getopts recognizes. If a letter is followed by
a :, that option is expected to have an argument. The options can be
separated from the argument by blanks.


getopts places the next option letter it finds inside variable name each
time it is invoked with a + prepended when arg begins with a +. The index
of the next arg is stored in OPTIND. The option argument, if any, gets
stored in OPTARG.


A leading : in optstring causes getopts to store the letter of an invalid
option in OPTARG, and to set name to ? for an unknown option and to :
when a required option is missing. Otherwise, getopts prints an error
message. The exit status is non-zero when there are no more options.


getopts supports both traditional single-character short options and long
options defined by Sun's Command Line Interface Paradigm (CLIP).


Each long option is an alias for a short option and is specified in
parentheses following its equivalent short option. For example, you can
specify the long option file as an alias for the short option f using the
following script line:

getopts "f(file)" opt


Precede long options on the command line with -- or ++. In the example
above, --file on the command line would be the equivalent of -f, and
++file on the command line would be the equivalent of +f.


Each short option can have multiple long option equivalents, although
this is in violation of the CLIP specification and should be used with
caution. You must enclose each long option equivalent parentheses, as
follows:

getopts "f:(file)(input-file)o:(output-file)"


In the above example, both --file and --input-file are the equivalent of
-f, and --output-file is the equivalent of -o.


The variable name is always set to a short option. When a long option is
specified on the command line, name is set to the short-option
equivalent.


For a further discussion of the Korn shell's getopts built-in command,
see the previous discussion in the Bourne shell (sh) section of this
manpage.

ksh93
The getopts utility can be used to retrieve options and arguments from a
list of arguments specified by args or the positional parameters if arg
is omitted. It can also generate usage messages and a manual page for the
command based on the information in optstring.


Each time it is invoked, the getopts utility places the value of the next
option in the shell variable specified by the name operand and the index
of the next argument to be processed in the shell variable OPTIND. When
the shell is invoked OPTIND is initialized to 1. When an option requires
or permits an option argument, getopts places the option argument in the
shell variable OPTARG. Otherwise OPTARG is set to 1 when the option is
set and 0 when the option is unset.


The optstring string consists of alphanumeric characters, the special
characters +, -, ?, :, and SPACE or character groups enclosed in [...].
Character groups can be nested in {...}. Outside of a [...] group, a
single NEWLINE followed by zero or more blanks is ignored. One or more
blank lines separate the options from the command argument synopsis.


Each [...] group consists of an optional label, optional attributes
separated by :, and an optional description string following ?. The
characters from the ? to the end of the next ] are ignored for option
parsing and short usage messages. They are used for generating verbose
help or man pages. The : character can not appear in the label. The ?
character must be specified as ?? in the label and the ] character must
be specified as ]] in the description string. Text between two \b
(backspace) characters indicates that the text should be emboldened when
displayed. Text between two \a (bell) characters indicates that the text
should be emphasized or italicized when displayed. Text between two \v
(vertical tab) characters indicates that the text should displayed in a
fixed-width font. Text between two \f (form feed) characters is replaced
by the output from the shell function whose name is that of the enclosed
text.


All output from this interface is written to the standard error.


There are several group types:

1. A group of the form

[-[version][flag[number]]...[?text]]


which appears as the first group enables the extended
interface.

version specifies the interface version, currently 1. The
latest version is assumed if version is omitted. Future
enhancements can increment version, but all versions are
supported. text typically specifies an SCCS or CVS
identification string. Zero or more flags with optional number
values can be specified to control option parsing. The flags
are:

c
Cache this optstring for multiple passes. Used to optimize
built-ins that can be called many times within the same process.


i
Ignore this optstring when generating help. Used when combining
optstring values from multiple passes.


l
Display only long option names in help messages.


o
The - option character prefix is optional. This supports the
obsolete ps(1) option syntax.


p
The number specifies the number of - characters that must prefix
long option names. The default is 2. 0, 1 or 2 are accepted, for
example p0 for dd(8) and p1 for find(1).


s
The number specifies the manual page section number, 1 by
default.


2. An option specification of the form
[option[!][=number][:longname][?text]]. In this case the
first field is the option character, which is the value
returned in the name operand when the option is matched. If
there is no option character then a two or more digit number
should be specified. This number is returned as the value of
the name operand if the long option is matched. If option is
followed by a ! then the option character sense is the inverse
of the longname sense. For options that do not take values
OPTARG is set to 0 for ! inverted option characters and 1
otherwise. =number optionally specifies a number to be
returned in the name operand instead of the option character.
A longname is specified by --longname and is matched by the
shortest non-ambiguous prefix of all long options. An * in the
longname field indicates that only characters up to that point
need to match, provided any additional characters match
exactly. The enclosing [ and ] can be omitted for an option
that does not have a longname or descriptive text.

3. An option argument specification. Options that take arguments
can be followed by :, indicating a string value or #,
indicating a numeric value, and an option argument
specification. An option argument specification consists of
the option argument name as field 1. The remaining : separated
fields are a type name and zero or more of the special
attribute words listof, oneof, and ignorecase. A default
option value can be specified in the final field as :=default.
The option argument specification can be followed by a list of
option value descriptions enclosed in braces. A long option
that takes an argument is specified as --longname=value. If
the : or # is followed by ?, the option argument is optional.
If only the option character form is specified then the
optional argument value is not set if the next argument starts
with - or +.

4. An option value description.

5. An argument specification. A list of valid option argument
values can be specified by enclosing them inside a {...}
following the option argument specification. Each of the
permitted values can be specified with a [...] containing the
value followed by a description.

6. A group of the form [+\n...] displays the characters
representing ... in fixed-width font without adding line
breaks.

7. A group of the form [+name?text] specifies a section name with
descriptive text. If name is omitted, text is placed in a new
paragraph.

8. A group of the form [-name?text] specifies entries for the
IMPLEMENTATION section.


If the leading character of optstring is +, arguments beginning with +
are also be considered options.


A leading : character or a : following a leading + in optstring affects
the way errors are handled. If an option character or longname argument
not specified in optstring is encountered when processing options, the
shell variable whose name is name is set to the ? character. The shell
variable OPTARG is set to the character found. If an option argument is
missing or has an invalid value, then name is set to the : character and
the shell variable OPTARG is set to the option character found. Without
the leading :, name is set to the ? character, OPTARG is unset, and an
error message is written to standard error when errors are encountered.


The end of options occurs when:

1. The special argument -- is encountered.

2. An argument that does not begin with a - is encountered.

3. A help argument is specified.

4. An error is encountered.


If OPTIND is set to the value 1, a new set of arguments can be used.


getopts can also be used to generate help messages containing command
usage and detailed descriptions. Specify args as:

-?
Use this to generate a usage synopsis.


--??
Use this to generate a verbose usage message.


--??man
Use this to generate a formatted manual page.


--??api
Use this to generate an easy to parse usage message.


--??html
Use this to generate a man page in html format.


--??nroff
Use this to generate a man page in nroff format.


--??usage
Use this to list the current optstring.


--???name
Use this to list version=n, where n is greater than 0, if
the option name is recognized by getopts.


When the end of options is encountered, getopts exits with a non-zero
return value and the variable OPTIND is set to the index of the first
non-option argument.

OPTIONS


ksh93
The following options are supported by ksh93:

-a name
Use name instead of the command name in usage messages.


OPERANDS


The following operands are supported:

optstring
A string containing the option characters recognised by the
utility invoking getopts. If a character is followed by a
colon, the option is expected to have an argument, which
should be supplied as a separate argument. Applications
should specify an option character and its option-argument
as separate arguments, but getopts interprets the characters
following an option character requiring arguments as an
argument whether or not this is done. An explicit null
option-argument need not be recognised if it is not supplied
as a separate argument when getopts is invoked; see
getopt(3C). The characters question-mark (?) and colon (:)
must not be used as option characters by an application. The
use of other option characters that are not alphanumeric
produces unspecified results. If the option-argument is not
supplied as a separate argument from the option character,
the value in OPTARG is stripped of the option character and
the -. The first character in optstring determines how
getopts behaves if an option character is not known or an
option-argument is missing.


name
The name of a shell variable that is set by the getopts
utility to the option character that was found.


The getopts utility by default parses positional parameters passed to the
invoking shell procedure. If args are specified, they are parsed instead
of the positional parameters.

USAGE


Since getopts affects the current shell execution environment, it is
generally provided as a shell regular built-in. If it is called in a
subshell or separate utility execution environment, such as one of the
following:

(getopts abc value "$@")
nohup getopts ...
find . -exec getopts ... \;


it does not affect the shell variables in the caller's environment.


Notice that shell functions share OPTIND with the calling shell even
though the positional parameters are changed. Functions that want to use
getopts to parse their arguments usually want to save the value of OPTIND
on entry and restore it before returning. However, there are cases when a
function wants to change OPTIND for the calling shell.

EXAMPLES


Example 1: Parsing and Displaying Arguments




The following example script parses and displays its arguments:


aflag=
bflag=
while getopts ab: name
do
case $name in
a) aflag=1;;
b) bflag=1
bval="$OPTARG";;
?) printf "Usage: %s: [-a] [-b value] args\n" $0
exit 2;;
esac
done
if [ ! -z "$aflag" ]; then
printf "Option -a specified\n"
fi
if [ ! -z "$bflag" ]; then
printf 'Option -b "%s" specified\n' "$bval"
fi
shift $(($OPTIND - 1))
printf "Remaining arguments are: %s\n" "$*"


Example 2: Processing Arguments for a Command with Options




The following fragment of a shell program processes the arguments for a
command that can take the options -a or -b. It also processes the option
-o, which requires an option-argument:


while getopts abo: c
do
case $c in
a | b) FLAG=$c;;
o) OARG=$OPTARG;;
\?) echo $USAGE
exit 2;;
esac
done
shift `expr $OPTIND - 1`


Example 3: Equivalent Code Expressions




This code example accepts any of the following as equivalent:


cmd -a -b -o "xxx z yy" filename
cmd -a -b -o "xxx z yy" -- filename
cmd -ab -o xxx,z,yy filename
cmd -ab -o "xxx z yy" filename
cmd -o xxx,z,yy -b -a filename


ENVIRONMENT VARIABLES


See environ(7) for descriptions of the following environment variables
that affect the execution of getopts: LANG, LC_ALL, LC_CTYPE,
LC_MESSAGES, and NLSPATH.

OPTIND
This variable is used by getopts as the index of the next
argument to be processed.


OPTARG
This variable is used by getopts to store the argument if an
option is using arguments.


EXIT STATUS


The following exit values are returned:

0
An option, specified or unspecified by optstring, was found.


>0
The end of options was encountered or an error occurred.


ksh93
The following exit values are returned by ksh93:

0
A specified option was found.


1
An end of options was encountered.


2
A usage or information message was generated.


ATTRIBUTES


See attributes(7) for descriptions of the following attributes:

/usr/bin/getopts, sh, ksh


+--------------------+-------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-------------------+
|Interface Stability | Committed |
+--------------------+-------------------+
|Standard | See standards(7). |
+--------------------+-------------------+

ksh93


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Uncommitted |
+--------------------+-----------------+

SEE ALSO


Intro(1), getoptcvt(1), ksh(1), ksh93(1), ps(1), sh(1), getopt(3C),
attributes(7), environ(7), standards(7)

DIAGNOSTICS


Whenever an error is detected and the first character in the optstring
operand is not a colon (:), a diagnostic message is written to standard
error with the following information in an unspecified format:

o The invoking program name is identified in the message. The
invoking program name is the value of the shell special
parameter 0 at the time the getopts utility is invoked. A name
equivalent to

basename "$0"

can be used.

o If an option is found that was not specified in optstring,
this error is identified and the invalid option character is
identified in the message.

o If an option requiring an option-argument is found, but an
option-argument is not found, this error is identified and the
invalid option character is identified in the message.


November 2, 2007 GETOPTS(1)