vl-filename-mktemp (AutoLISP)

Calculates a unique file name to be used for a temporary file

Supported Platforms: Windows and Mac OS

Signature

(vl-filename-mktemp [pattern directory extension])

pattern

Type: String

File name pattern; if nil or absent, vl-filename-mktemp uses “$VL~~”.

directory

Type: String

Directory for temporary files; if nil or absent, vl-filename-mktemp chooses a directory in the following order:

• The directory specified in pattern, if any.
• The directory specified in the TMP environment variable.
• The directory specified in the TEMP environment variable.
• The current directory.

extension

Type: String

Extension to be assigned to the file; if nil or absent, vl-filename-mktemp uses the extension part of pattern (which may be an empty string).

Return Values

Type: String

A textual value containing a file name, in the following format:

directory\base<XXX><.extension>

where:

base is up to 5 characters, taken from pattern

XXX is a 3-character unique combination

All file names generated by vl-filename-mktemp during a session are deleted when you exit the application.

Release Information

Releases:

• AutoCAD R14 and later on Windows
• AutoCAD 2011 and later on Mac OS

History

AutoCAD 2021

• pattern, directory and extension arguments previously accepted ASCII text strings, but they now accept Unicode text strings.
• Return value was modified to support Unicode characters and might be different than earlier releases. For example, (vl-filename-mktemp "myapp" "c:\\abc中") previously returned a temporary file name in the path identified by the directory argument, but now correctly returns a temporary file name based on the directory provided to the function.
• LISPSYS system variable controls which AutoLISP engine is used and the behavior of the function.
  • 0 - ASCII character support (legacy behavior)
  • 1 or 2 - Unicode character support
  Note: After the value of the LISPSYS system variable has been changed, AutoCAD must be restarted for the change to take affect.

Examples

Windows

(vl-filename-mktemp)
"C:\\TMP\\$VL~~004"

(vl-filename-mktemp "myapp.del")
"C:\\TMP\\MYAPP005.DEL"

(vl-filename-mktemp "c:\\acadwin\\myapp.del")
"C:\\ACADWIN\\MYAPP006.DEL"

(vl-filename-mktemp "c:\\acadwin\\myapp.del")
"C:\\ACADWIN\\MYAPP007.DEL"

(vl-filename-mktemp "myapp" "c:\\acadwin")
"C:\\ACADWIN\\MYAPP008"

(vl-filename-mktemp "myapp" "c:\\acadwin" ".del")
"C:\\ACADWIN\\MYAPP00A.DEL"

Mac OS

(vl-filename-mktemp)
"/documents/$VL~~001"

(vl-filename-mktemp "myapp.del")
"/documents/MYAPP002.DEL"

(vl-filename-mktemp "/myutilities/temp/myapp.del")
"/myutilities/temp/MYAPP003.DEL"

(vl-filename-mktemp "/myutilities/temp/myapp.del")
"/myutilities/temp/MYAPP004.DEL"

(vl-filename-mktemp "myapp" /myutilities/temp")
"/myutilities/temp/MYAPP005"

(vl-filename-mktemp "myapp" "/myutilities/temp" ".del")
"/myutilities/temp/MYAPP006.DEL"