GET_LUN Procedure

Allocates a file unit from a pool of free units.

Usage

GET_LUN, unit

Input Parameters

unit—A named variable.

Output Parameters

unit—On output, unit is converted into an integer containing the file unit number.

Keywords

None.

Discussion

GET_LUN sets unit to the first available logical unit number. This number can then be used to open a file.

User-written PV-WAVE functions and procedures should use GET_LUN to reserve unit numbers to avoid conflicts with other routines. (Similarly, they should use FREE_LUN to free them when finished).

Note: The Get_Lun keyword, used with the OPENR, OPENU, and OPENW procedures, calls GET_LUN to allocate a file unit number.

Example

Suppose that the first available logical unit number is 100.

; Return the logical unit number to allocate (100).
GET_LUN, log_unit
; Open test.dat file for reading. Then read the file.
OPENR, log_unit, !Data_Dir + 'mandril.img'
my_var = BYTARR(512, 512)
READU, log_unit, my_var
; Closes the file and frees the logical unit 100.
FREE_LUN, log_unit