SH-ARG(1) SH-ARG(1)
NAME
arg - shell command-line argument parsing
SYNOPSIS
load arg
arg [ opts command ]... - args
DESCRIPTION
Arg is a loadable module for sh(1) that parses command-line
arguments in the same form as arg(2). It accepts a list of
(opts, command) pairs, where each character in opts is an
acceptable option, and command is a shell command to be run
if any character in opts is found. Any trailing plus (+)
characters in opts cause arg to extract the same number of
arguments associated with the option before running command.
For the duration of command, the environment variable $opt
will be set to the option that has been found, and $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 usage exception raised). The option charac-
ter asterisk (*) 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 usage exception raised.
The list of option specifications is terminated with a sin-
gle minus (-); the arguments to be parsed follow this. When
the argument parsing has finished the environment variable
$* is set to the remaining list of arguments.
EXAMPLE
The following shell script, script, takes options b, c and
f, where f takes a file name argument.
#!/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 $*
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SH-ARG(1) SH-ARG(1)
When invoked as follows:
script -bc -r 0 10 50 100 -ffile a b c
the output is:
./script 1 1 file
rect 0 10 50 100
arguments are a b c
and when invoked by:
script -b -f file -z -- -bc
the output is:
unknown option z
./script 1 0 file
arguments are -bc
SOURCE
/appl/cmd/sh/arg.b
SEE ALSO
sh(1), arg(2), sh-std(1)
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