getopts - parse utility options
/usr/bin/getopts optstring name [ arg...]
getopts optstring name [argument...]
getopts optstring name [arg...]
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 will be initialised to 1.
When the option requires an option-argument, the getopts
utility will place 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 will be 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 will be set to the
question-mark ( ? ) character. In this case, if the first
character in optstring is a colon (:, the shell variable
OPTARG will be set to the option character found, but no
output will be written to standard error; otherwise, the
shell variable OPTARG will be unset and a diagnostic message
will be written to standard error. This condition is con-
sidered 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 will be set to the
colon character and the shell variable OPTARG will be
set to the option character found.
o Otherwise, the shell variable specified by name will
be set to the question-mark character (?), the shell
variable OPTARG will be unset, and a diagnostic mes-
sage will be written to standard error. This condition
is considered to be an error detected in the way argu-
ments were presented to the invoking application, but
is not an error in getopts processing; a diagnostic
message will be written as stated, but the exit status
will be zero.
When the end of options is encountered, the getopts utility
will exit with a return value greater than zero; the shell
variable OPTIND will be 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 will be set
to the question-mark character. Any of the following identi-
fies the end of options: the special option --, finding an
argument that does not begin with a -, or encountering an
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
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 will recognize; 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
When an option requires an option-argument, getopts places
it in the shell variable OPTARG.
If an illegal option is encountered, ? will be placed in
When the end of options is encountered, getopts exits with a
non-zero exit status. The special option - may 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 will 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 may 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
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 may lead to unexpected results.
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.
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.
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.
The following operands are supported:
A string containing the option characters recognised
by the utility invoking getopts. If a character is
followed by a colon, the option will be 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 will interpret 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 charac-
ters by an application. The use of other option char-
acters 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 will be stripped of the option character and
the -. The first character in optstring will determine
how getopts will behave if an option character is not
known or an option-argument is missing.
name The name of a shell variable that will be set by the
getopts utility to the option character that was
The getopts utility by default will parse positional parame-
ters passed to the invoking shell procedure. If args are
given, they will be parsed instead of the positional parame-
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 will not affect the shell variables in the caller's
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
will usually want to save the value of OPTIND on entry and
restore it before returning. However, there will be cases
when a function will want to change OPTIND for the calling
Example 1: Parsing and displaying arguments
The following example script parses and displays its argu-
while getopts ab: name
case $name in
?) printf "Usage: %s: [-a] [-b value] args\n" $0
if [ ! -z "$aflag" ]; then
printf "Option -a specified\n"
if [ ! -z "$bflag" ]; then
printf 'Option -b "%s" specified\n' "$bval"
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 shows how one
might process the arguments for a command that can take the
options -a or -b, as well as the option -o, which requires
while getopts abo: c
case $c in
a | b) FLAG=$c;;
\?) echo $USAGE
shift `expr $OPTIND - 1`
Example 3: Equivalent code expressions
This code 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
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.
This variable is used by getopts as the index of the
next argument to be processed.
This variable is used by getopts to store the argument
if an option is using arguments.
The following exit values are returned:
0 An option, specified or unspecified by optstring, was
>0 The end of options was encountered or an error
See attributes(5) for descriptions of the following attri-
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| Availability | SUNWcsu |
| Interface Stability | Standard |
intro(1), getoptcvt(1), ksh(1), sh(1), getopt(3C), attri-
butes(5), environ(5), standards(5)
Whenever an error is detected and the first character in the
optstring operand is not a colon (:), a diagnostic message
will be written to standard error with the following infor-
mation in an unspecified format:
o The invoking program name will be identified in the
message. The invoking program name will be the value
of the shell special parameter 0 at the time the
getopts utility is invoked. A name equivalent to
may be used.
o If an option is found that was not specified in opt-
string, this error will be identified and the invalid
option character will be identified in the message.
o If an option requiring an option-argument is found,
but an option-argument is not found, this error will
be identified and the invalid option character will be
identified in the message.
Man(1) output converted with