# 9. Session directory

PRRTE establishes a “session directory” on the filesystem to serve as a top-level location for temporary files used by both the local PRRTE daemon and its child processes.

This is done to enable quick and easy cleanup in the event that PRRTE is unable to fully cleanup after itself.

## 9.1. Directory location

PRRTE decides where to located the root of the session directory by examining the following (in precedence order):

1. If the value of the `prte_top_session_dir` MCA parameter is not empty, use that (it defaults to empty).

   Note

   MCA parameters can be set via environment variables, on the command line, or in a parameter file.

2. If the environment variable `TMPDIR` is not empty, use that.

3. If the environment variable `TEMP` is not empty, use that.

4. If the environment variable `TMP` is not empty, use that.

5. Use `/tmp`

## 9.2. Directory name

By default, the session directory name is set to

    prte.<nodename>.<uid>

The session directory name can further be altered to include the PID of the daemon process, if desired:

    prte.<nodename>.<pid>.<uid>

by setting the `prte_add_pid_to_session_dirname` MCA parameter to a “true” value (e.g., 1).

## 9.3. Tools

In the case of tools, the rendezvous files containing connection information for a target server are located in the session directory tree. Thus, it may be necessary to point the tool at the location where those files can be found if that location is other than the expected default.