IDL command line arguments

-arg

Syntax: -arg value

Specifies a single command line option to be saved for later access via the COMMAND_LINE_ARGS function. The value string is saved. Multiple -arg switches are allowed; the values are saved in the order specified. The -arg option can be used to pass program-specific information from the command line to IDL programs.

-args

Syntax: -args value1 value2 ... valueN

Specifies one or more command line options to be saved for later access via the COMMAND_LINE_ARGS function. When IDL sees the -args option, it takes any command-line arguments that follow it and saves them all. There can only be one -args option on an IDL command line, and it is always the final option. The -args switch can be used with the -arg switch; if both switches are specified, occurrences of -arg must come first, and the values specified by -args are saved following any values specified by -arg.

The COMMAND_LINE_ARGS function returns strings supplied by the user when IDL was started with the -arg or -args command line options. If either of these options is specified at the command line when IDL is started, IDL saves them without examining their values or attaching any special meaning to them.

Note The shell performs its normal interpretation of wildcards and shell metacharacters before the values of the -arg or -args command line options are passed to IDL.

Strings specified at the command line can be retrieved at any time within the IDL session via the COMMAND_LINE_ARGS function. This mechanism can be used to pass special application-defined values to a program written in the IDL language.

Syntax

Result = COMMAND_LINE_ARGS( [, COUNT=variable] )

Return Value

If any -arg or -args options were specified at the command line when IDL was started, COMMAND_LINE_ARGS returns a string array containing the specified values, one value per element. The values are returned in the order specified by the user on the command line. If no such options were specified, a NULL scalar string is returned.

Keywords

COUNT

Set this keyword equal to a named variable that will contain the number of retrieved arguments. If no arguments were specified, the variable will contain 0.

The COMMAND_LINE_ARGS routine was introduced in IDL 6.2, allowing IDL programs to access command line args passed to IDL when starting it. For example, to pass command line arguments into the MYPROGRAM routine, call IDL like below:

$ idl -e "myprogram" -args a b c

Then, in MYPROGRAM, the command line arguments could be retrieved with:

args = command_line_args()

The args string array would contain “a”, “b”, and “c”. To make it more convenient to launch IDL this way, you can create a script that calls IDL in the proper way, passing arguments of the script to arguments listed after the -args in the IDL call. If you name the wrapper script myprogram also, your calls would look like:

$ myprogram a b c