.\" $NetBSD: getopt.1,v 1.8 1997/10/19 02:16:57 lukem Exp $ .Dd June 21, 1993 .Dt GETOPT 1 .Os .Sh NAME .Nm getopt .Nd parse command options .Sh SYNOPSIS .Li args=\`getopt optstring $*\` .Pp .Li set \-\- \`getopt optstring $*\` .Sh DESCRIPTION .Nm is used to break up options in command lines for easy parsing by shell procedures, and to check for legal options. .Op Optstring is a string of recognized option letters (see .Xr 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 white space. The special option .Dq \-\- is used to delimit the end of the options. .Nm will place .Dq \-\- in the arguments at the end of the options, or recognize it if used explicitly. The shell arguments (\fB$1 $2\fR ...) are reset so that each option is preceded by a .Dq \- and in its own shell argument; each option argument is also in its own shell argument. .Sh EXAMPLE The following code fragment shows how one might process the arguments for a command that can take the options .Op a and .Op b , and the option .Op o , which requires an argument. .Pp .Bd -literal -offset indent args=\`getopt abo: $*\` if test $? != 0 then echo 'Usage: ...' exit 2 fi set \-\- $args for i do case "$i" in \-a|\-b) flag=$i; shift;; \-o) oarg=$2; shift; shift;; \-\-) shift; break;; esac done .Ed .Pp This code will accept any of the following as equivalent: .Pp .Bd -literal -offset indent cmd \-aoarg file file cmd \-a \-o arg file file cmd \-oarg -a file file cmd \-a \-oarg \-\- file file .Ed .Pp .St -p1003.2 mandates that the .Xr sh 1 set command return the value of 0 for the exit status. Therefore, the exit status of the .Nm command is lost when .Nm and the .Xr sh 1 set command are used on the same line. The example given is one way to detect errors found by .Nm "" . .Sh SEE ALSO .Xr sh 1 , .Xr getopt 3 .Sh DIAGNOSTICS .Nm prints an error message on the standard error output when it encounters an option letter not included in .Op optstring . .Sh HISTORY Written by Henry Spencer, working from a Bell Labs manual page. Behavior believed identical to the Bell version. .Sh BUGS Whatever .Xr getopt 3 has. .Pp Arguments containing white space or embedded shell metacharacters generally will not survive intact; this looks easy to fix but isn't. .Pp The error message for an invalid option is identified as coming from .Nm rather than from the shell procedure containing the invocation of .Nm "" ; this again is hard to fix. .Pp The precise best way to use the .Ic set command to set the arguments without disrupting the value(s) of shell options varies from one shell version to another.