[apple/shell_cmds.git] / getopt / getopt.1

.\"	$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.
Commit	Line	Data
44bd5ea7 A	1	.\" $NetBSD: getopt.1,v 1.8 1997/10/19 02:16:57 lukem Exp $
	2	.Dd June 21, 1993
	3	.Dt GETOPT 1
	4	.Os
	5	.Sh NAME
	6	.Nm getopt
	7	.Nd parse command options
	8	.Sh SYNOPSIS
	9	.Li args=\`getopt optstring $*\`
	10	.Pp
	11	.Li set \-\- \`getopt optstring $*\`
	12	.Sh DESCRIPTION
	13	.Nm
	14	is used to break up options in command lines for easy parsing by
	15	shell procedures, and to check for legal options.
	16	.Op Optstring
	17	is a string of recognized option letters (see
	18	.Xr getopt 3
	19	);
	20	if a letter is followed by a colon, the option
	21	is expected to have an argument which may or may not be
	22	separated from it by white space.
	23	The special option
	24	.Dq \-\-
	25	is used to delimit the end of the options.
	26	.Nm
	27	will place
	28	.Dq \-\-
	29	in the arguments at the end of the options,
	30	or recognize it if used explicitly.
	31	The shell arguments
	32	(\fB$1 $2\fR ...) are reset so that each option is
	33	preceded by a
	34	.Dq \-
	35	and in its own shell argument;
	36	each option argument is also in its own shell argument.
	37	.Sh EXAMPLE
	38	The following code fragment shows how one might process the arguments
	39	for a command that can take the options
	40	.Op a
	41	and
	42	.Op b ,
	43	and the option
	44	.Op o ,
	45	which requires an argument.
	46	.Pp
	47	.Bd -literal -offset indent
	48	args=\`getopt abo: $*\`
	49	if test $? != 0
	50	then
	51	echo 'Usage: ...'
	52	exit 2
	53	fi
	54	set \-\- $args
	55	for i
	56	do
	57	case "$i"
	58	in
	59	\-a\|\-b)
	60	flag=$i; shift;;
	61	\-o)
	62	oarg=$2; shift; shift;;
	63	\-\-)
	64	shift; break;;
65	esac
66	done
67	.Ed
68	.Pp
69	This code will accept any of the following as equivalent:
70	.Pp
71	.Bd -literal -offset indent
72	cmd \-aoarg file file
73	cmd \-a \-o arg file file
74	cmd \-oarg -a file file
75	cmd \-a \-oarg \-\- file file
76	.Ed
77	.Pp
78	.St -p1003.2
79	mandates that the
80	.Xr sh 1
81	set command return the value of 0 for the exit status. Therefore,
82	the exit status of the
83	.Nm
84	command is lost when
85	.Nm
86	and the
87	.Xr sh 1
88	set command are used on the same line. The example given
89	is one way to detect errors found by
90	.Nm "" .
91	.Sh SEE ALSO
92	.Xr sh 1 ,
93	.Xr getopt 3
94	.Sh DIAGNOSTICS
95	.Nm
96	prints an error message on the standard error output when it
97	encounters an option letter not included in
98	.Op optstring .
99	.Sh HISTORY
100	Written by Henry Spencer, working from a Bell Labs manual page.
101	Behavior believed identical to the Bell version.
102	.Sh BUGS
103	Whatever
104	.Xr getopt 3
105	has.
106	.Pp
107	Arguments containing white space or embedded shell metacharacters
108	generally will not survive intact; this looks easy to fix but isn't.
109	.Pp
110	The error message for an invalid option is identified as coming
111	from
112	.Nm
113	rather than from the shell procedure containing the invocation
114	of
115	.Nm "" ;
116	this again is hard to fix.
117	.Pp
118	The precise best way to use the
119	.Ic set
120	command to set the arguments without disrupting the value(s) of
121	shell options varies from one shell version to another.