dollar

Type

keyword

Summary

The character $ (dollar sign) is used to indicate an environment variable on Unix systems and a command-line parameter on Unix or Windows systems.

Syntax

$

Description

Use the $ keyword to interact with the system environment and to find out what arguments were used if the application was started up from the command line.

The $ character marks two kinds of special variables: command-line arguments (on OS X, Unix, and Windows systems) and environment variables (on OS X and Unix systems).

If you start up the application from the command line (on OS X, Unix or Windows systems), the command name is stored in the global variable $0 and any arguments passed on the command line are stored in numbered variables starting with the $ character. For example, if you start the application by typing the following shell command:

    myrevapp -h name

then the global variable $0 contains "myrevapp" (the name of the application), $1 contains "-h", and $2 contains "name".

If an argument includes spaces, it must be enclosed in quotes on the command line:

    myrevapp -in \"new info.txt\"  -out \"new info.xml\"

On Unix and OS X systems, a variable whose name begins with the $ character is exported to the application's environment, and is inherited by processes started up by the shell function or the open process command. Use this technique to create your own environment variables.

You can access existing environment variables by prepending the $ character to the environment variable's name. For example, the following statement gets the contents of the LOGNAME environment variable:

    get $LOGNAME

Examples

put $LOGNAME into field "Login Name"

if $0 is not "myAppName" then answer "Problem initializing!"

Related

keyword: at

message: relaunch

command: open process

control structure: function, setProp

function: paramCount, shell

glossary: application, variable, command line, argument, command, Windows, environment variable, OS X, keyword, Unix, statement, process

Compatibility and Support

Introduced

LiveCode 1.0

OS

mac

windows

linux

ios

android

Platforms

desktop

server

mobile