www.delorie.com/gnu/docs/m4/m4_65.html

search

	Buy GNU books!

GNU macro processor

12.4 Making names for temporary files

Commands specified to syscmd or esyscmd might need a temporary file, for output or for some other purpose. There is a builtin macro, maketemp, for making temporary file names:

maketemp(template)

which expands to a name of a non-existent file, made from the string template, which should end with the string `XXXXXX'. The six X's are then replaced, usually with something that includes the process id of the m4 process, in order to make the filename unique.

maketemp(`/tmp/fooXXXXXX') =>/tmp/fooa07346 maketemp(`/tmp/fooXXXXXX') =>/tmp/fooa07346

As seen in the example, several calls of maketemp might expand to the same string, since the selection criteria is whether the file exists or not. If a file has not been created before the next call, the two macro calls might expand to the same name.

The builtin macro maketemp is recognized only when given arguments.