z/OS V1R9.0 UNIX System Services Command ... - Christian Grothoff

getopts
Example
script recognizes –a, –f, and –s, opstring is afs. If you want an option letter
to be followed by an argument value or group of values, put a colon after
the letter, as in a:fs. This indicates that getopts expects the –a option to
have the form –a value. Normally one or more blanks separate value from
the option letter; however, getopts also handles values that follow the letter
immediately, as in –avalue. opstring cannot contain a question mark (?)
character.
name Specifies the name of a shell variable. Each time you invoke getopts, it
obtains the next option from the positional parameters and places the
option letter in the shell variable name.
getopts places a question mark (?) in name if it finds an option that does
not appear in opstring, or if an option value is missing.
arg ... Each option on the script command line has a numeric index. The first
option found has an index of 1, the second has an index of 2, and so on.
When getopts obtains an option from the script command line, it stores the
index of the script in the shell variable OPTIND.
When an option letter has a following argument (indicated with a : in
opstring), getopts stores the argument as a string in the shell variable
OPTARG. If an option doesn’t take an argument, or if getopts expects an
argument but doesn’t find one, getopts unsets OPTARG.
When getopts reaches the end of the options, it exits with a status value of
1. It also sets name to the character ? and sets OPTIND to the index of the
first argument after the options. getopts recognizes the end of the options
by any of the following:
v Finding an argument that doesn’t start with –
v Finding the special argument ––, marking the end of options
v Encountering an error (for example, an unrecognized option letter)
OPTIND and OPTARG are local to the shell script. If you want to export
them, you must do so explicitly. If the script invoking getopts sets OPTIND
to 1, it can call getopts again with a new set of parameters, either the
current positional parameters or new arg values.
By default, getopts issues an error message if it finds an unrecognized
option or some other error. If you do not want such messages printed,
specify a colon as the first character in opstring.
Following is an example of using getopts in a shell script:
# Example illustrating use of getopts builtin. This
# shell script would implement the paste command,
# using getopts to process options, if the underlying
# functionality was embedded in hypothetical utilities
# hpaste and vpaste, which perform horizontal and
# vertical pasting respectively.
#
paste=vpaste # default is vertical pasting
seplist="" # default separator is tab
while getopts d:s o
do case "$o" in
d) seplist="$OPTARG";;
s) paste=hpaste;;
[?]) print >&2 "Usage: $0 [-s] [-d seplist] file ..."
exit 1;;
302 z/OS V1R9.0 UNIX System Services Command Reference