Parse command-line arguments: Difference between revisions
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=={{header|Rust}}== |
=={{header|Rust}}== |
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Using the [https://docs.rs/structopt StructOpt]: |
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<lang rust>use structopt::StructOpt; |
<lang rust>use structopt::StructOpt; |
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Revision as of 19:23, 4 October 2019
Command-line arguments can be quite complicated, as in:
- nc -v -n -z -w 1 192.168.1.2 1-1000
Many languages provide a library (getopt or GetOpt) to parse the raw command line options in an intelligent way.
AutoHotkey
For AutoHotkey v1.1+ <lang AutoHotkey>;Get Arguments as an array if 0 > 0 { argc=%0% args:=[] Loop, %argc% args.Insert(%A_Index%) } else { ;if got no arguments, run self with arguments Run,%a_scriptFullpath% -i Lib\* -c files.c --verbose -o files.o --Optimze ExitApp }
- Parse arguments
i:=0, msg:="" while( i++ < argc ) { c:=SubStr(args[i],1,1) if c in -,/ ; List all switch chars { if ( SubStr(args[i],1,2) == "--" ) ; if "--" is used like "--verbose" msg:=msg args[i] "`t:`tTrue (Boolean)`n" ; parse as boolean else msg:=msg args[i] "`t:`t" args[++i] "`n" } else msg:=msg args[i] "`t:`t(normal)`n" }
MsgBox % "Parsed Arguments :`n" msg</lang> Output (MsgBox):
Parsed Arguments : -i : Lib\* -c : files.c --verbose : True (Boolean) -o : files.o --Optimze : True (Boolean)
AWK
<lang awk>#!/usr/bin/awk -E
- -E instead of -f so program arguments don't conflict with Gawk arguments
@include "getopt.awk" BEGIN {
while ((C = getopt(ARGC, ARGV, "ht:u:")) != -1) {
opti++
if(C == "h") {
usage()
exit
}
if(C == "t")
tval = Optarg
if(C == "u")
uval = Optarg
}
print "There are " opti " arguments."
if(tval) print "-t = " tval
if(uval) print "-u = " uval
}</lang>
Bracmat
Per default, Bracmat treats all arguments as expressions and parses and evaluates them from left to right. A call to the function arg$ pops the next argument from the list of arguments and returns it as an inert string in no need of further parsing and evaluation.
bracmat arg$:?a 123 arg$:?b 77 !a+!b:?c out$!c
Output:
200
C
The man page for getopt (man 3 getopt) provides better option handling with examples. But if you just want to parse one argument... (adapted from simple database task): <lang c>#include <stdio.h> int main(int argc, char **argv){
int i;
const char *commands[]={"-c", "-p", "-t", "-d", "-a", NULL};
enum {CREATE,PRINT,TITLE,DATE,AUTH};
if (argc<2) {
usage: printf ("Usage: %s [commands]\n"
"-c Create new entry.\n"
"-p Print the latest entry.\n"
"-t Sort by title.\n"
"-d Sort by date.\n"
"-a Sort by author.\n",argv[0]);
return 0;
}
for (i=0;commands[i]&&strcmp(argv[1],commands[i]);i++);
switch (i) {
case CREATE:
...
break; case PRINT:
...
break;
... ...
default:
printf ("Unknown command..." ...);
goto usage;
}
return 0;
}</lang>
Clojure
See Parsing Command-Line Arguments from O'Reilly's Clojure Cookbook github.
D
The getopt module in D's standard library is inspired by Perl's Getopt::Long module. The syntax of Phobos getopt infers the expected parameter types from the static types of the passed-in pointers. <lang d>import std.stdio, std.getopt;
void main(string[] args) {
string data = "file.dat";
int length = 24;
bool verbose;
enum Color { no, yes }
Color color;
args.getopt("length", &length, // Integer.
"file", &data, // String.
"verbose", &verbose, // Boolean flag.
"color", &color); // Enum.
writeln("length: ", length);
writeln("file: ", data);
writeln("verbose: ", verbose);
writeln("color: ", color);
}</lang>
- Usage example:
C:\getopt_test --verbose --length 12 length: 12 file: file.dat verbose: true color: no
Elixir
Elixir provides an option parser in a library module called OptionParser.
<lang elixir>#!/usr/bin/env elixir IO.puts 'Arguments:' IO.inspect OptionParser.parse(System.argv())</lang>
<lang bash>$ ./parse-args.exs --a --b --c=yes --no-flag --verbose -V -a=1 -b=t -- apple banana Arguments: {[a: true, b: true, c: "yes", no_flag: true, verbose: true],
["apple", "banana"], [{"-V", nil}, {"-a", "1"}, {"-b", "t"}]}</lang>
FreeBASIC
<lang freebasic>' FB 1.05.0 Win64
' Program (commandline.exe) invoked like this: ' commandline nc -v -n -z -w 1 192.168.1.2 1-1000
Dim argc As Integer = __FB_ARGC__ Dim argv As ZString Ptr Ptr = __FB_ARGV__
Print "The program was invoked with the following command line arguments:" Print
For i As Integer = 0 To argc - 1
Print "Arg"; i + 1; " = "; *argv[i]
Next
Print Print "Press any key to quit" Sleep</lang>
- Output:
The program was invoked with the following command line arguments: Arg 1 = commandline Arg 2 = nc Arg 3 = -v Arg 4 = -n Arg 5 = -z Arg 6 = -w Arg 7 = 1 Arg 8 = 192.168.1.2 Arg 9 = 1-1000
Go
Most simply, implementing the suggested example from the talk page: <lang go>package main
import (
"flag" "fmt"
)
func main() {
b := flag.Bool("b", false, "just a boolean")
s := flag.String("s", "", "any ol' string")
n := flag.Int("n", 0, "your lucky number")
flag.Parse()
fmt.Println("b:", *b)
fmt.Println("s:", *s)
fmt.Println("n:", *n)
}</lang> Example runs:
> parse b: false s: n: 0 > parse -s bye -b b: true s: bye n: 0 > parse -n 99 -s "say my name" b: false s: say my name n: 99
Icon and Unicon
The Icon Programming Library provides a procedure for processing command line options. See the library reference for detailed documentation. The code below is an example.
<lang Icon>link options
procedure main(ARGLIST) /errproc := stop # special error procedure or stop() opstring := "f!s:i+r.flag!string:integer+real." # example opttable := options(ARGLIST,optstring,errproc)
if \opttable[flag] then ... # test a flag r := opttable(real) # assign a real r2 := opttable(r) # assign another real s := opttable(s) # assign a string i := opttable(i) # assign an integer ... end</lang>
options.icn supports getting command-line options
J
When J starts up from the command line, the command line arguments are available in the array ARGV. On modern machines, the first command line argument is the name of the executable (the J interpeter, in this case).
Typically, the next argument (if present) is the name of a file whose contents will be executed.
Further command line analysis might include:
- Test if an argument is present:
- <lang j> (<'-b') e. ARGV</lang>
- This is true if the argument is present and false, if it is not.
- Or, find the name of an optional file:
- <lang j> (ARGV i.<'-f') {:: }.ARGV,a:</lang>
- This is the name of the first file named after the first -f argument, or empty if there was no such file.
Other concepts are also possible...
Julia
Example taken from the official documentation of ArgParse docs.
<lang julia>using ArgParse
function parse_commandline()
s = ArgParseSettings()
@add_arg_table s begin
"--opt1"
help = "an option with an argument"
"--opt2", "-o"
help = "another option with an argument"
arg_type = Int
default = 0
"--flag1"
help = "an option without argument, i.e. a flag"
action = :store_true
"arg1"
help = "a positional argument"
required = true
end
return parse_args(s)
end
function main()
parsed_args = parse_commandline()
println("Parsed args:")
for (arg,val) in parsed_args
println(" $arg => $val")
end
end
main()</lang>
Kotlin
<lang scala>// version 1.0.6 (packaged as parse_cla.jar)
fun main(args: Array<String>) = println(args.asList())</lang>
- Output:
c:\kotlin-compiler-1.0.6>java -jar parse_cla.jar nc -v -n -z -w 1 192.168.1.2 1-1000 [nc, -v, -n, -z, -w, 1, 192.168.1.2, 1-1000]
Mathematica
The command line is parsed and stored into a list of strings to ease manual handling by list processing functions. <lang Mathematica> $CommandLine -> {math, -v, -n, -z, -w, 1, 192.168.1.2, 1-1000} </lang>
PARI/GP
GP exists in a REPL and so it doesn't make sense to parse command-line arguments. But PARI can parse them just like C: <lang c>#include <pari/pari.h>
- include <stdio.h>
int main(int argc, char **argv){ if(strcmp(argv[1],"-n")) pari_printf("8 + 1 = %Ps\n", addii(int2u(3), gen_1)); return 0; }</lang>
Nim
<lang nim>import os import parseopt
proc main =
# Directly accessing the app name and parameters echo "app name: ", getAppFilename().extractFilename() echo "# parameters: ", paramCount() for ii in 1 .. paramCount(): # 1st param is at index 1 echo "param ", ii, ": ", paramStr(ii)
echo ""
# Using parseopt module to extract short and long options and arguments var argCtr : int
for kind, key, value in getOpt():
case kind
of cmdArgument:
echo "Got arg ", argCtr, ": \"", key, "\""
argCtr.inc
of cmdLongOption, cmdShortOption:
case key
of "v", "n", "z", "w":
echo "Got a \"", key, "\" option with value: \"", value, "\""
else:
echo "Unknown option: ", key
of cmdEnd:
discard
main()
</lang>
Sample command line:
parsecmdline ab -z cd ef -w=abcd --w=1234 -v -e -x 1-1000
Output:
app name: parsecmdline # parameters: 10 param 1: ab param 2: -z param 3: cd param 4: ef param 5: -w=abcd param 6: --w=1234 param 7: -v param 8: -e param 9: -x param 10: 1-1000 Got arg 0: "ab" Got a "z" option with value: "" Got arg 1: "cd" Got arg 2: "ef" Got a "w" option with value: "abcd" Got a "w" option with value: "1234" Got a "v" option with value: "" Unknown option: e Unknown option: x Got arg 3: "1-1000"
Perl
Use the Getopt::Long module:
<lang perl># Copyright Shlomi Fish, 2013 under the MIT/X11 License.
use strict; use warnings;
use Getopt::Long qw(GetOptions); my $output_path; my $verbose = ; my $length = 24;
GetOptions(
"length=i" => \$length, "output|o=s" => \$output_path, "verbose!" => \$verbose,
) or die ("Error in command line arguments");
print "Outputting to '", ($output_path // '(undefined)'), "' path, with ",
($verbose ? "Verbosity" : "No verbosity"), " and a length of $length.\n";
</lang>
The output from it is:
$ perl getopt-test.pl --verbose -o foo.xml Outputting to 'foo.xml' path, with Verbosity and a length of 24. $ perl getopt-test.pl --verbose Outputting to '(undefined)' path, with Verbosity and a length of 24. $ perl getopt-test.pl --verbose --length=190 Outputting to '(undefined)' path, with Verbosity and a length of 190. $ perl getopt-test.pl --verbose --length=190 -o test.txt Outputting to 'test.txt' path, with Verbosity and a length of 190.
Perl 6
At the end of running any top-level code (which can preprocess the arguments if it likes), Perl 6 automatically examines any remaining arguments and transforms them into a call to a MAIN routine, if one is defined. The arguments are parsed based on the signature of the routine, so that options are mapped to named arguments. <lang perl6>sub MAIN (Bool :$b, Str :$s = , Int :$n = 0, *@rest) {
say "Bool: $b"; say "Str: $s"; say "Num: $n"; say "Rest: @rest[]";
}</lang>
- Output:
$ ./main -h Usage: ./main [-b] [-s=<Str>] [-n=<Int>] [<rest> ...] $ ./main -b -n=42 -s=turtles all the way down Bool: True Str: turtles Num: 42 Rest: all the way down
If there are multiple MAIN subs, they are differentiated by multiple dispatch. A help message can automatically be generated for all the variants. The intent of this mechanism is not to cover every possible switch structure, but just to make it drop-dead easy to handle most of the common ones.
Phix
<lang Phix>sequence res = command_line() ?res</lang>
- Output:
Interpreted: res[1] is the interpreter, res[2] the source
> p test nc -v -n -z -w 1 192.168.1.2 1-1000
{"C:\\Program Files (x86)\\Phix\\p.exe","C:\\Program Files (x86)\\Phix\\test.exw","nc","-v","-n","-z","-w","1","192.168.1.2","1-1000"}
Compiled: both res[1] and res[2] are the executable
> p -c test nc -v -n -z -w 1 192.168.1.2 1-1000
{"C:\\Program Files (x86)\\Phix\\test.exe","C:\\Program Files (x86)\\Phix\\test.exe","nc","-v","-n","-z","-w","1","192.168.1.2","1-1000"}
> test nc -v -n -z -w 1 192.168.1.2 1-1000
{"C:\\Program Files (x86)\\Phix\\test.exe","C:\\Program Files (x86)\\Phix\\test.exe","nc","-v","-n","-z","-w","1","192.168.1.2","1-1000"}
Python
Version 2.3+ <lang Python> from optparse import OptionParser [...] parser = OptionParser() parser.add_option("-f", "--file", dest="filename",
help="write report to FILE", metavar="FILE")
parser.add_option("-q", "--quiet",
action="store_false", dest="verbose", default=True,
help="don't print status messages to stdout")
(options, args) = parser.parse_args()
example:
<yourscript> --file=outfile -q </lang>
PicoLisp
PicoLisp doesn't have a library to get options. Instead, the command line is parsed at startup and handled in the following way: Each command line argument is executed (interpreted) as a Lisp source file, except that if the first character is a hypen '-', then that arguments is taken as a Lisp function call (without the surrounding parentheses). For example, the command line <lang shell>$ ./pil abc.l -foo def.l -"bar 3 4" -'mumble "hello"' -bye</lang> has the effect that
- The file "abc.l" is executed
- (foo) is called
- The file "def.l" is executed
- (bar 3 4) is called
- (mumble "hello") is called
- (bye) is called, resulting in program termination
Command line arguments like "-v", "-n" and "-z" can be implemented simply by defining three functions 'v', 'n' and 'z'.
In addition to the above mechanism, the command line can also be handled "manually", by either processing the list of arguments returned by 'argv', or by fetching arguments individually with 'opt'.
PowerShell
Powershell functions and filters handle options organically, with advanced .NET support to handle complex and advanced options including aliases, ranges, sets, datatypes, and more. See more here. However, to parse options 'classically', you can write a custom parser. A slightly messy version (inspired by ruby optparse) that can only handle switches and relies on RegEx: <lang Powershell> $options = @{
opt1 = [bool] 0
opt2 = [bool] 0
opt3 = [bool] 0
}
$help = @"
FUNCTION usage: FUNCTION [-p] [-w] [-h] [-c] <int><float><string>PARAMETERS...
Lorem Ipsum blah blah blah
NOTE something yada yada
Options:
-p,--pxx Name Some option that has significance with the letter 'p'
-w,--wxx Name Some option that has significance with the letter 'w'
-c,--cxx Name Some option that has significance with the letter 'c'
-h,--help Help Prints this message
"@
function parseOptions ($argv,$options) {
$opts = @()
if (!$argv) { return $null }
foreach ($arg in $argv) {
# Make sure the argument is something you are expecting
$test = ($arg -is [int]) -or
($arg -is [string]) -or
($arg -is [float])
if (!$test) {
Write-Host "Bad argument: $arg is not an integer, float, nor string." -ForegroundColor Red
throw "Error: Bad Argument"
}
if ($arg -like '-*') { $opts += $arg }
}
$argv = [Collections.ArrayList]$argv
if ($opts) {
foreach ($opt in $opts) {
switch ($opt) {
{'-p' -or '--pxx'} { $options.opt1 = [bool] 1 }
{'-w' -or '--wxx'} { $options.opt2 = [bool] 1 }
{'-c' -or '--cxx'} { $options.opt3 = [bool] 1 }
{'-h' -or '--help'} { Write-Host $help -ForegroundColor Cyan; break 1 }
default {
Write-Host "Bad option: $opt is not a valid option." -ForegroundColor Red
throw "Error: Bad Option"
}
}
$argv.Remove($opt)
}
}
return [array]$argv,$options
}#fn
</lang> Usage (in some function or script): <lang Powershell>
$argv,$options = parseOptions $args $options
if ($options.opt3) {
$foo = $blah - ($yada * $options.opt1) + ($yada * $options.opt2)
$bar = $argv | SomeOtherFilter | Baz
}
</lang> Usage in shell: <lang shell> $> function -c --wxx arg1 arg2 </lang> Note that this works in Powershell. All of the arguments after the function name will be passed as strings to the function, which then calls them as an array with the automatic variable, $args. The custom parser/function does the work from there, turning the strings into flags and typed arguments. WARNING: This is reinventing the wheel to an extreme degree.
Racket
Racket has a good command-line parsing library, the following demonstrates some of its features:
<lang racket>
- !/usr/bin/env racket
- lang racket
(define loglevel 1) (define mode 'new) (define ops '()) (define root #f)
(command-line
#:multi
[("-v" "--verbose") "more verbose" (set! loglevel (add1 loglevel))]
[("-q" "--quiet") "be quiet" (set! loglevel 0)]
#:once-any
[("-i" "--in-place") "edit in-place" (set! mode 'in-place)]
[("-c" "--create-new") "create a new file" (set! mode 'new)]
[("-n" "--dry-run") "do nothing" (set! mode #f)]
#:once-each
[("-d" "--directory") dir "work in a given directory" (set! root dir)]
#:help-labels "operations to perform:"
#:multi
[("+l" "++line") "add a line" (set! ops `(,@ops "add"))]
[("-l" "--line") "delete a line" (set! ops `(,@ops "delete"))]
[("-e" "--edit") "edit a line" (set! ops `(,@ops "edit"))]
#:args (file . files)
(printf "Running on: ~a\n" (string-join (cons file files) ", "))
(when root (printf "In Dir: ~a\n" root))
(printf "Mode: ~s\n" mode)
(printf "Log level: ~s\n" loglevel)
(printf "Operations: ~a\n" (string-join ops ", ")))
</lang>
Sample runs:
$ ./foo -h foo [ <option> ... ] <file> [<files>] ... where <option> is one of * -v, --verbose : more verbose * -q, --quiet : be quiet / -i, --in-place : edit in-place | -c, --create-new : create a new file \ -n, --dry-run : do nothing -d <dir>, --directory <dir> : work in a given directory operations to perform: * +l, ++line : add a line * -l, --line : delete a line * -e, --edit : edit a line --help, -h : Show this help -- : Do not treat any remaining argument as a switch (at this level) * Asterisks indicate options allowed multiple times. /|\ Brackets indicate mutually exclusive options. Multiple single-letter switches can be combined after one `-'; for example: `-h-' is the same as `-h --' $ /tmp/zz.rkt -viqvvd /tmp +ll -el foo bar baz Running on: foo, bar, baz In Dir: /tmp Mode: in-place Log level: 2 Operations: add, add, edit, delete
REXX
╔═════════════════════════════════════════════════════════════════════════════╗ ║ The subject of parsing text (such as a command line) is ingrained in the ║ ║ REXX language; it has a PARSE instruction. It's too rich to describe all ║ ║ its functionality/capabilities here, but since the task isn't described, ║ ║ I'm assuming the NC [NetCat] example (or something like it) is toe ║ ║ be parsed, and I'm guessing at its syntax (from other examples found on ║ ║ the web), but I'll take a incomplete stab at it. ║ ║ ║ ║ For the most part, every command appear to have their own rules for their ║ ║ operands (options), as does the NC command. For instance ║ ║ ║ ║ nc -u xxx -p port1 ··· ║ ║ and ║ ║ nc -u -p port1 ··· ║ ║ ║ ║ where the -u option has an operand in the first case, but not the 2nd, ║ ║ even though there is something following the -u option. ║ ║ ║ ║ It can only be assumed that any operand for the -u option can't start ║ ║ with a minus sign [-]. ║ ╚═════════════════════════════════════════════════════════════════════════════╝
<lang rexx>/*REXX program demonstrates one method to parse options for a command (entered on the CL*/ parse arg opts /*this preserves the case of options. */ opts=space(opts) /*elide superfluous blanks in options. */ !.= /*all options to be "null" (default).*/
do while opts\== /*keep parsing 'til all opts examined*/ parse var opts x opts /*obtain a single keyword from options.*/
select /*hard-coded WHENs for option detection*/
when x=='-e' then parse var opts !.e_ opts
when x=='-p' then parse var opts !.p_ opts
when x=='-n' then !.z_=1
when x=='-u' then parse var opts !.uname_ !.unnn_ opts
when x=='-ul' then parse var opts !.ul_ opts
when x=='-vzu' then parse var opts !.vzu_ !.vzurange opts
when x=='-w' then parse var opts !.wStart_ !.waddr_ !.wrange_1 '-' !.wrange_2 opts
when x=='-z' then !.=1
otherwise call sayer 'option ' x " isn't a known option."
end /*select*/
end /*do while*/
/*check for conflicts here and/or validity of values.*/
if !.z_==1 & !.n_==1 then call sayer "N and Z can't both be specified."
if !.wrange_1\== then do /*see if it's a whole number (integer). */
if \isInt(!.wrange1_) then call sayer "wRange isn't an integer."
yada yada yada
.
.
.
end
...stuff...
...more stuff...
...and still more stuff... exit /*stick a fork in it, we're all done. */ /*──────────────────────────────────────────────────────────────────────────────────────*/ isInt: return datatype(arg(1), 'W') /*return 1 if argument is an integer*/ isNum: return datatype(arg(1), 'N') /*return 1 if argument is a number.*/ sayer: say; say '***error***' arg(1); exit 13</lang>
╔═══════════════════════════════════════════════════════════════════════╗ ║ Note: a programming trick is to append (say) an underscore [_] to ║ ║ an option's name as to not preclude that variable being used ║ ║ elsewhere in the REXX program. That way, the option J can ║ ║ be used, as well as the variable J in the program. ║ ╚═══════════════════════════════════════════════════════════════════════╝
Ruby
Ruby's standard library provides two different packages to parse command-line arguments.
- 'getoptlong' resembles the libraries from other languages.
- 'optparse' has more features.
Ruby with 'getoptlong'
<lang ruby>#!/usr/bin/env ruby
- == Synopsis
- pargs: Phone a friend
- == Usage
- pargs [OPTIONS]
- --help, -h:
- show usage
- --eddy, -e <message>
- call eddy
- --danial, -d <message>
- call daniel
- --test, -t
- run unit tests
require "getoptlong" require "rdoc/usage"
def phone(name, message) puts "Calling #{name}..." puts message end
def test phone("Barry", "Hi!") phone("Cindy", "Hello!") end
def main mode = :usage
name = "" message = ""
opts=GetoptLong.new( ["--help", "-h", GetoptLong::NO_ARGUMENT], ["--eddy", "-e", GetoptLong::REQUIRED_ARGUMENT], ["--daniel", "-d", GetoptLong::REQUIRED_ARGUMENT], ["--test", "-t", GetoptLong::NO_ARGUMENT] )
opts.each { |option, value| case option when "--help" RDoc::usage("Usage") when "--eddy" mode = :call name = "eddy" message = value when "--daniel" mode = :call name = "daniel" message = value when "--test" mode = :test end }
case mode when :usage RDoc::usage("Usage") when :call phone(name, message) when :test test end end
if __FILE__==$0 begin main rescue Interrupt => e nil end end</lang>
$ ./pargs.rb -h Usage ----- pargs [OPTIONS] --help, -h: show usage --eddy, -e <message> call eddy --daniel, -d <message> call daniel --test, -t run unit tests $ ./pargs.rb -e Yo! Calling eddy... Yo! $ ./pargs.rb --test Calling Barry... Hi! Calling Cindy... Hello!
Ruby with 'optparse'
<lang ruby>require 'optparse'
sflag = false longflag = false count = 0 percent = 50 fruit = nil
OptionParser.new do |opts|
# Default banner is "Usage: #{opts.program_name} [options]".
opts.banner += " [arguments...]"
opts.separator "This demo prints the results of parsing the options."
opts.version = "0.0.1"
opts.on("-s", "Enable short flag") {sflag = true}
opts.on("--long", "Enable long flag") {longflag = true}
opts.on("-b", "--both", "Enable both -s and --long"
) {sflag = true; longflag = true}
opts.on("-c", "--count", "Add 1 to count") {count += 1}
# Argument must match a regular expression.
opts.on("-p", "--percent PERCENT", /[0-9]+%?/i,
"Percent [50%]") {|arg| percent = arg.to_i}
# Argument must match a list of symbols.
opts.on("-f", "--fruit FRUIT",
[:apple, :banana, :orange, :pear],
"Fruit (apple, banana, orange, pear)"
) {|arg| fruit = arg}
begin # Parse and remove options from ARGV. opts.parse! rescue OptionParser::ParseError => error # Without this rescue, Ruby would print the stack trace # of the error. Instead, we want to show the error message, # suggest -h or --help, and exit 1.
$stderr.puts error $stderr.puts "(-h or --help will show valid options)" exit 1 end
end
print <<EOF Short flag: #{sflag} Long flag: #{longflag} Count: #{count} Percent: #{percent}% Fruit: #{fruit} Arguments: #{ARGV.inspect} EOF</lang>
$ ruby takeopts.rb -h
Usage: takeopts [options] [arguments...]
This demo prints the results of parsing the options.
-s Enable short flag
--long Enable long flag
-b, --both Enable both -s and --long
-c, --count Add 1 to count
-p, --percent PERCENT Percent [50%]
-f, --fruit FRUIT Fruit (apple, banana, orange, pear)
$ ruby takeopts.rb -v
takeopts 0.0.1
$ ruby takeopts.rb -b -c
Short flag: true
Long flag: true
Count: 1
Percent: 50%
Fruit:
Arguments: []
$ ruby takeopts.rb -ccccp90% -f oran -- -arg
Short flag: false
Long flag: false
Count: 4
Percent: 90%
Fruit: orange
Arguments: ["-arg"]
Rust
Using the StructOpt:
<lang rust>use structopt::StructOpt;
- [derive(StructOpt)]
struct Opt {
#[structopt(short)] b: bool, #[structopt(short, required = false, default_value = "")] s: String, #[structopt(short, required = false, default_value = "0")] n: i32,
}
fn main() {
let opt = Opt::from_args();
println!("b: {}", opt.b);
println!("s: {}", opt.s);
println!("n: {}", opt.n);
}</lang>
Examples:
> parse b: false s: n: 0 > parse -s bye -b b: true s: bye n: 0 > parse -n 99 -s "say my name" b: false s: say my name n: 99
Scala
<lang Scala>object CommandLineArguments extends App {
println(s"Received the following arguments: + ${args.mkString("", ", ", ".")}")
}</lang>
Standard ML
The following code listing can be compiled with both SML/NJ and MLton: <lang sml>structure Test = struct
exception FatalError of string
fun main (prog, args) = (let exception Args
val switch = ref false
fun do_A arg = print ("Argument of -A is " ^ arg ^ "\n") fun do_B () = if !switch then print "switch is on\n" else print "switch is off\n"
fun usage () = print ("Usage: " ^ prog ^ " [-help] [-switch] [-A Argument] [-B]\n")
fun parseArgs nil = () | parseArgs ("-help" :: ts) = (usage(); parseArgs ts) | parseArgs ("-switch" :: ts) = (switch := true; parseArgs ts) | parseArgs ("-A" :: arg :: ts) = (do_A arg; parseArgs ts) | parseArgs ("-B" :: ts) = (do_B(); parseArgs ts) | parseArgs _ = (usage(); raise Args)
in parseArgs args handle Args => raise FatalError "Error parsing args. Use the -help option."; (* Do something; *) OS.Process.success end) handle FatalError e => (print ("Fatal Error:\n"^e^"\n"); OS.Process.failure) end
(* MLton *) val _ = Test.main (CommandLine.name(), CommandLine.arguments())</lang>
SML/NJ
SML/NJ can compile source code to a "heap file", witch can than be executed by the interpreter with arguments given (see this entry on stackowerflow.com for more information).
The source.cm file should lock like this:
<lang>Group
is
SOURCE_FILE.sml $/basis.cm</lang>
To compile the program, use ml-build sources.cm. This should create a "heap file" sources.x86-linux, depending on your architecture.
The heap file can be executed with sml @SMLload=sources.x86-linux ARGUMENTS, or the script heap2exec can be used to make a single executable.
MLton
MLton compiles the source file directly to a executable by invoking mlton SOURCE_FILE.sml.
Tcl
The following proc detects and removes argument-less (-b) and one-argument options from the argument vector. <lang Tcl>proc getopt {_argv name {_var ""} {default ""}} {
upvar 1 $_argv argv $_var var
set pos [lsearch -regexp $argv ^$name]
if {$pos>=0} {
set to $pos
if {$_var ne ""} {set var [lindex $argv [incr to]]}
set argv [lreplace $argv $pos $to]
return 1
} else {
if {[llength [info level 0]] == 5} {set var $default}
return 0
}
}</lang>
Usage examples:
getopt argv -sep sep ";" ;# possibly override default with user preference set verbose [getopt argv -v] ;# boolean flag, no trailing word
Searching with -regexp allows to specify longer mnemonic names, so it still succeeds on longer flags, e.g.
$ myscript.tcl -separator '\t' ...
zkl
The Argh class provides command line parsing, it can do actions during parsing, leave it for you to do after parsing, print errors, the option list, short or long options, with or without option args, etc.
File myprogram.zkl: <lang zkl>var ip; argh := Utils.Argh( T("v","v","print version",fcn{println("Version stub")}), T("n","n","ignored"), T("z","z","zazzle"), T("+ip","","get IP address",fcn(arg){ip=arg}), ); parsedArgs := argh.parse(vm.arglist);
println("Unparsed stuff: ",argh.loners); println("The IP address is ",ip); foreach option,arg in (parsedArgs){
switch(option) {
case("z") { println("zazzle") }
}
}</lang>
zkl myprogram nc -v -n -z --ip 192.168.1.2 1-1000
- Output:
Version stub
Unparsed stuff: L("nc","1-1000")
The IP address is 192.168.1.2
zazzle
zkl myprogram nc -v -n -z --ip
- Output:
Option "ip" is missing an arg Options: --ip <arg>: get IP address --n (-n) : ignored --v (-v) : print version --z (-z) : zazzle