getopts(1)getopts(1)NAMEgetopts - parse utility (command) options
optstring name [arg ...]
is used to retrieve options and option-arguments from a list of parame‐
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 applica‐
tion, but is not an error in processing.
If an option-argument is missing:
· 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.
· Otherwise, the shell variable specified by name is set to the
question-mark character, the shell variable is unset, and a
diagnostic 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
The shell variable specified by the name operand, and affect the cur‐
rent shell execution environment.
The following operands are supported:
optstring A string containing the option characters recog‐
nized 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 char‐
acters 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 ques‐
tion-mark and colon must not be used as option
characters by an application. The use of other
option characters that are not alphanumeric pro‐
duces unspecified results. If the option-argu‐
ment is not supplied as a separate argument 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 util‐
Used by as the index of the next argument to be pro‐
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 information in an unspecified format:
· The invoking program name will be identified in the message.
The invoking program name will be the value of the shell spe‐
cial parameter 0 at the time the utility is invoked. A name
may be used.
· If an option is found that was not specified in optstring,
this error will be identified and the invalid option charac‐
ter will be identified in the message.
· 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
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\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" "$*"
SEE ALSOgetopt(1), ksh(1), sh-posix(1), sh(1), getopt(3C).