getopt - parse command options
set -- `getopt optstring $*`
getopt is used to break up options in command lines for easy
shell procedures, and to check for legal options. [optstring] is a
string of recognized option letters (see getopt(3)); if a
letter is followed
by a colon, the option is expected to have an argument
which may or
may not be separated from it by whitespace. The special option ``--'' is
used to delimit the end of the options. getopt will place
``--'' in the
arguments at the end of the options, or recognize it if used
The shell arguments ($1 $2 ...) are reset so that each option is preceded
by a ``-'' and in its own shell argument; each option argument is also in
its own shell argument.
The following code fragment shows how one might process the
a command that can take the options -a and -b, and the option -o, which
requires an argument.
set -- `getopt abo: $*`
if test $? != 0
echo 'Usage: ...'
oarg=$2; shift; shift;;
This code will accept any of the following as equivalent:
cmd -aoarg file file
cmd -a -o arg file file
cmd -oarg -a file file
cmd -a -oarg -- file file
getopt prints an error message on the standard error output
when it encounters
an option letter not included in [optstring].
Written by Henry Spencer, working from a Bell Labs manual
believed identical to the Bell version.
Whatever getopt(3) has.
Arguments containing whitespace or embedded shell metacharacters generally
will not survive intact; this looks easy to fix but
The error message for an invalid option is identified as
getopt rather than from the shell procedure containing the
getopt; this again is hard to fix.
The precise best way to use the set command to set the arguments without
disrupting the value(s) of shell options varies from one
shell version to
OpenBSD 3.6 June 21, 1993
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