g.tempfile: allow creation of temporary directories

general/g.tempfile/g.tempfile.html

@@ -1,19 +1,25 @@
 <h2>DESCRIPTION</h2>
 
 <em>g.tempfile</em>
-is designed for shell scripts that need to use large temporary files.
-GRASS provides a mechanism for temporary files that does not depend on
-/tmp. GRASS temporary files are created in the data base with the assumption
-that there will be enough space under the data base for large files.
+creates a unique temporary file or directory (<b>-f</b>) and prints the path.
+It is designed for shell scripts that need to use large temporary files.
+GRASS provides a mechanism for temporary files or directories that does not
+depend on /tmp. GRASS temporary files and directories are created in the
+GRASS GIS database with the assumption that there will be enough space for
+large files. The base directory is: $PROJECT/$MAPSET/.tmp/$HOSTNAME/
+
+<p>
 GRASS periodically removes temporary files that have been left behind
 by programs that failed to remove them before terminating.
 
 <p>
-<em>g.tempfile</em>
-creates an unique file and prints the name. The user is required to provide
-a process-id which will be used as part of the name of the file.
-Most Unix shells provide a way to get the process id of the current shell.
-For /bin/sh and /bin/csh this is $$.
+<em>g.tempfile</em> requires the user to provide an integer number,
+usually a process-id (<b>pid</b>), which will be used as part of the file or
+directory name of the resulting path, suffixed by a dot and the 0-indexed
+number of temporary files with that PID.
+
+Most Unix shells provide a way to get the
+process id of the current shell. For /bin/sh and /bin/csh this is $$.
 It is recommended that $$ be specified as the process-id for
 <em>g.tempfile</em>.
 
@@ -23,6 +29,11 @@ <h2>EXAMPLE</h2>
 <div class="code"><pre>
 temp1=`g.tempfile pid=$$`
 temp2=`g.tempfile pid=$$`
+# Get the tempile path but do not create it
+temp3=`g.tempfile -d pid=$$`
+# Create a temporary directory
+temp3=`g.tempfile -f pid=$$`
+
 </pre></div>
 For /bin/csh scripts, the following can be used:
 <div class="code"><pre>
@@ -36,12 +47,30 @@ <h2>NOTES</h2>
 creates a different (i.e. unique) name.
 
 Although GRASS does eventually get around to removing
-tempfiles that have been left behind, the programmer should
-make every effort to remove these files. They often get
-large and take up disk space. If you write /bin/sh scripts,
-learn to use the /bin/sh <em>trap</em> command. If you
-write /bin/csh scripts, learn to use the /bin/csh
-<em>onintr</em> command.
+temporary files and directories that have been left behind,
+the programmer should make every effort to remove these files.
+They often get large and take up disk space. If you write /bin/sh
+scripts, learn to use the /bin/sh <em>trap</em> command. If you
+write /bin/csh scripts, learn to use the /bin/csh <em>onintr</em>
+command. In Python, use an <em>atexit</em> procedure.
+
+<p>
+If the size of temporary files is not an issue, it is recommended
+to use <i>NamedTemporaryFile</i> with a context manager to create a
+temporary file in Python.<br>
+In this example below, we open a temporary file for writing,
+write something and then we can use it in another tool.
+Once we do not need it anymore, we need to delete it ourselves.
+
+<div class="code"><pre>
+import tempfile
+
+with tempfile.NamedTemporaryFile(mode="w", delete=False) as tmp_file:
+    file_path = tmp_file.name
+    tmp_file.write(...)
+
+gs.try_remove(file_path)
+</pre></div>
 
 <h2>AUTHOR</h2>
 

general/g.tempfile/main.c

@@ -29,6 +29,7 @@ int main(int argc, char *argv[])
     struct GModule *module;
     struct Option *pid;
     struct Flag *dry_run;
+    struct Flag *directory;
     char *tempfile;
     int p;
 
@@ -52,6 +53,13 @@ int main(int argc, char *argv[])
     dry_run->description =
         _("Dry run - don't create a file, just prints it's file name");
 
+    directory = G_define_flag();
+    directory->key = 'f';
+    directory->description =
+        _("Folder mode - create a temporary directory, not a file");
+
+    G_option_exclusive(dry_run, directory, NULL);
+
     G_disable_interactive();
     if (G_parser(argc, argv))
         exit(EXIT_FAILURE);
@@ -63,8 +71,12 @@ int main(int argc, char *argv[])
     tempfile = G_tempfile_pid(p);
 
     /* create tempfile so next run of this program will create a unique name */
-    if (!dry_run->answer)
-        close(creat(tempfile, 0666));
+    if (!dry_run->answer) {
+        if (directory->answer)
+            G_mkdir(tempfile);
+        else
+            close(creat(tempfile, 0666));
+    }
     fprintf(stdout, "%s\n", tempfile);
 
     exit(EXIT_SUCCESS);

python/grass/script/core.py

@@ -955,11 +955,13 @@ def tempfile(create=True, env=None):
 
 
 def tempdir(env=None):
-    """Returns the name of a temporary dir, created with g.tempfile."""
-    tmp = tempfile(create=False, env=env)
-    os.mkdir(tmp)
+    """Returns the name of a temporary directory, created with g.tempfile.
 
-    return tmp
+    :param env: environment
+
+    :return: path to a temporary directory
+    """
+    return read_command("g.tempfile", flags="f", pid=os.getpid(), env=env).strip()
 
 
 def tempname(length, lowercase=False):