getopts(1) General Commands Manual getopts(1)
getopts - parse utility (command) options
optstring name [arg ...]
is used to retrieve options and option-arguments from a list of parameters.
Each time it is invoked, places the value of the next option in the shell variable specified by the operand and the index of the next argu-
ment to be processed in the shell variable Whenever the shell is invoked, is initialized to 1.
When the option requires an option-argument, places it in the shell variable If no option was found, or if the option that was found does
not have an option-argument, 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 is set to
the option character found, but no output is written to standard error; otherwise, the shell variable 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 appli-
cation, but is not an error in 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 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 is unset, and a diag-
nostic message is written to the standard error. This condition is considered to be an error detected in the way arguments are
presented to the invoking application, but is not an error in processing; a diagnostic message is written as stated, but the exit
status is zero.
When the end of options is encountered, exits with a return value greater than zero. The shell variable is set to the index of the first
nonoption-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 nonoption-arguments; the name variable is set to the question-mark character. Any of the fol-
lowing identifies the end of options: the special option finding an argument that does not begin with a or encountering an error.
The shell variables and are local to the caller of and are not exported by default.
The shell variable specified by the name operand, and affect the current shell execution environment.
The following operands are supported:
optstring A string containing the option characters recognized by the utility invoking 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 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 is invoked. 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 argu-
ment from the option character, the value in will be stripped of the option character and the The first character in
optstring will determine how will behave if an option character is not known or an option-argument is missing.
name The name of a shell variable that is set by to the option character that was found.
by default parses positional parameters passed to the invoking shell procedures. If args are given, they are parsed instead of the posi-
The following environment variable affects the execution of the utility:
Used by as the index of the next argument to be processed.
Whenever an error is detected and the first character in the optstring operand is not a colon a diagnostic message will be written to stan-
dard error with the following information 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 utility is invoked. A name equivalent to:
may be used.
o If an option is found that was not specified in optstring, 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.
Since 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:
it does not affect the shell variables in the caller's environment.
Note that shell functions share with the calling shell even though the positional parameters are changed. Functions that use to parse
their arguments should save the value of on entry and restore it before returning. However, there will be cases when a function must
change for the calling shell.
The following example script parses and displays its arguments:
while getopts ab: name
case $name in
printf "Usage: %s: [-a] [-b value] args
if [ ! -z "$aflag" ] ; then
printf "Option -a specified
if [ ! -z "$bflag" ] ; then
printf "Option -b "%s" specified
shift $(($OPTIND -1))
printf "Remaining arguments are: %s
getopt(1), ksh(1), sh-posix(1), sh(1), getopt(3C).