argsCommand line flag parser for Murex shell scripting
One of the nuisances of shell scripts is handling flags. More often
than not your script will be littered with $1 still
variables and not handle flags shifting in placement amongst a group of
parameters. args aims to fix that by providing a common
tool for parsing flags.
args takes a name of a variable to assign the result of
the parsed parameters as well as a JSON structure containing the result.
It also returns a non-zero exit number if there is an error when
parsing.
args var-name { json-block } -> <stdout>#!/usr/bin/env murex
# First we define what parameters to accept:
# Pass the `args` function a JSON string (because JSON objects share the same braces as murex block, you can enter JSON
# directly as unescaped values as parameters in murex).
#
# --str: str == string data type
# --num: num == numeric data type
# --bool: bool == flag used == true, missing == false
# -b: --bool == alias of --bool flag
args args %{
AllowAdditional: true
Flags: {
--str: str
--num: num
--bool: bool
-b: --bool
}
}
catch {
# Lets check for errors in the command line parameters. If they exist then
# print the error and then exit.
err $args.error
exit 1
}
out "The structure of \$args is: ${$args->pretty}\n\n"
# Some example usage:
# -------------------
!if { $(args.Flags.--bool) } {
out "Flag `--bool` was not set."
}
# `<!null>` redirects the STDERR to a named pipe. In this instance it's the 'null' pipe so equivalent to 2>/dev/null
# thus we are just suppressing any error messages.
try <!null> {
$(args.Flags.--str) -> set fStr
$(args.Flags.--num) -> set fNum
out "Defined Flags:"
out " --str == $(fStr)"
out " --num == $(fNum)"
}
catch {
err "Missing `--str` and/or `--num` flags."
}
$args[Additional] -> foreach flag {
out "Additional argument (ie not assigned to a flag): `$(flag)`."
}Flags are any values pass via - or --
prefixed labels. For example --datatype str would assign
the value str to the flag name --datatype.
Flags can be str, int num
bool. These values will be type checked and
args will return an error if a user passes (for example)
alpha character to a numeric flag.
Boolean flags do not require true nor false
values to be included; the absence of a boolean flag automatically sets
it to false, while the presence automatically sets it to
true.
Parameters are any values that are not assigned to a flag. For
example cat file1.txt file2.txt file3.txt.
Sometimes you’ll want parameters that look like flags. For example
calculator -3 + 2 where -3 might normally be
considered a flag.
There are two ways you can force args to read values as
a parameter:
-- flag to denote that everything which follows is a
parameter. eg calculator -- -3 + 2.StrictFlagPlacement and have the first parameter be
non-flag option. Eg calculator print -3 + 2. With
StrictFlagPlacement, anything including and proceeding a
parameter will always be parsed as a parameter regardless of whether it
looks like a flag or not.(here, calculator is a hypothetical command)
bool: Boolean
(primitive)int: Whole number
(primitive)num (number): Floating
point number (primitive)str (string): string
(primitive)This document was generated from builtins/core/management/shell_doc.yaml.
This site's content is rebuilt automatically from murex's source code after each merge to the master branch. Downloadable murex binaries are also built with the website.
Last built on Mon Feb 2 23:22:37 UTC 2026 against commit 8678ad88678ad89405c2bdd2a92b203f026bc3d46abc88f.
Current version is 7.2.1001 (unknown) which has been verified against tests cases.