ref: 9ca327dd06c30341d984bff84727ea451b428db7
dir: /man/1/sh-arg/
.TH SH-ARG 1
.SH NAME
arg \- shell command-line argument parsing
.SH SYNOPSIS
.B load arg
.br
.B arg
[
.I opts command
]...
.B -
.I args
.SH DESCRIPTION
.I Arg
is a loadable module for
.IR sh (1)
that parses command-line arguments in the same
form as
.IR arg (2).
It accepts a list of
.RI ( opts ,\ command )
pairs, where
each character in
.I opts
is an acceptable option, and
.I command
is a shell command to be run if any character
in
.I opts
is found.
Any trailing plus
.RB ( + )
characters in
.I opts
cause
.I arg
to extract the same number of arguments associated
with the option before running
.IR command .
For the duration of
.IR command ,
the environment variable
.B $opt
will be set to the option that has been found,
and
.B $arg
will be set to the option's arguments (if the correct number
of arguments have been extracted;
otherwise a message will be printed, and a
.B usage
exception raised).
The option character asterisk
.RB ( * )
matches any option letter (this must
be quoted, to avoid the usual special interpretation
by the shell).
Only one command will be run for any option found;
if there is no matching option letter, then
a default error message will be printed, and a
.B usage
exception raised.
.PP
The list of option specifications is terminated with a single
minus
.RB ( - );
the arguments to be parsed follow this.
When the argument parsing has finished
the environment variable
.B $*
is set to the remaining list of arguments.
.SH EXAMPLE
The following shell script,
.BR script ,
takes options
.BR b ,
.B c
and
.BR f ,
where
.B f
takes a file name argument.
.EX
#!/dis/sh
load arg
bflag := cflag := 0
file := ()
args := $*
(arg
bc {$opt^flag = 1}
f+ {file=$arg}
r++++ {rect=$arg}
'*' {echo unknown option $opt}
- $args
)
echo $0 $bflag $cflag $file
echo rect $rect
echo arguments are $*
.EE
.PP
When invoked as follows:
.IP
.B "script -bc -r 0 10 50 100 -ffile a b c"
.PP
the output is:
.IP
.EX
\&./script 1 1 file
rect 0 10 50 100
arguments are a b c
.EE
.PP
and when invoked by:
.IP
.B "script -b -f file -z -- -bc"
.PP
the output is:
.IP
.EX
unknown option z
\&./script 1 0 file
arguments are -bc
.EE
.SH SOURCE
.B /appl/cmd/sh/arg.b
.SH SEE ALSO
.IR sh (1),
.IR arg (2),
.IR sh-std (1)