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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...]
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
SunOS 5.10 Last change: 21 Jul 2004 1
User Commands getopts(1)
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 vari-
able 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 param-
eters 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 syn-
tax 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 argu-
ments, 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.
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User Commands getopts(1)
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 given on the getopts com-
mand line, getopts parses them instead.
/usr/lib/getoptcvt reads the shell script in filename, con-
verts 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 stan-
dard 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 posi-
tional parameters are used. An option argument begins with a
+ or a -. An option not beginning with + or - or the argu-
ment - 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.
SunOS 5.10 Last change: 21 Jul 2004 3
User Commands getopts(1)
getopts places the next option letter it finds inside vari-
able 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.
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
SunOS 5.10 Last change: 21 Jul 2004 4
User Commands getopts(1)
option is expected to have an argument,
which should be supplied as a separate argu-
ment. 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 charac-
ters 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 miss-
ing.
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 given,
they are parsed instead of the positional parameters.
USAGE
Since getopts affects the current shell execution environ-
ment, 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.
SunOS 5.10 Last change: 21 Jul 2004 5
User Commands getopts(1)
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 argu-
ments:
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`
SunOS 5.10 Last change: 21 Jul 2004 6
User Commands getopts(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(5) 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 argu-
ments.
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.
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | SUNWcsu |
|_____________________________|_____________________________|
| Interface Stability | Standard |
|_____________________________|_____________________________|
SunOS 5.10 Last change: 21 Jul 2004 7
User Commands getopts(1)
SEE ALSO
intro(1), getoptcvt(1), ksh(1), sh(1), getopt(3C), attri-
butes(5), environ(5), standards(5)
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 opt-
string, 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 identi-
fied and the invalid option character is identified in
the message.
SunOS 5.10 Last change: 21 Jul 2004 8
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