Prevent a directory in /tmp from being deleted

I use pam-tmpdir for this: it creates a user-private temporary directory at login. To set it up, add

session optional pam_tmpdir.so

to the appropriate PAM services; on a Debian-based system, installing the libpam-tmpdir package will offer to do this for you, or you can add the line to /etc/pam.d/common-session. The next time you log in, you’ll find a directory under /tmp/user with your user id, and TMP and TMPDIR set appropriately.

One solution would be to use a @reboot cron job:

@reboot mkdir -p "/tmp/$USER"

Adding this to your crontab with crontab -e would make it execute whenever the machine boots up.

Or, use

mkdir -p "/tmp/$USER"

in your shell's startup file.

In either case, you may also want to use

TMPDIR=/tmp/$USER
export TMPDIR

in your shell's startup file if you want to use that directory as the default temporary directory.

If you're running no a system with systemd and it uses systemd-tmpfiles to manage the cleanup, then you should configure the directory using that system.

Here's a full documentation. You can likely achieve what you want by creating /etc/tmpfiles.d/something.conf with contents like:

d     /tmp/your_username   0750 your_user your_group  - -