Do Something With A Temporary Directory

A subprocess is often an ideal wrapper for a given task.

An often sought for wrapper is that of creating a temporary directory to make room for some scratch-space to work with, and to purge the directory when the task is done.

Although popular programming languages have mechanisms for doing this inside the language (e.g., a try-catch-finally, defer, or trap statement), there is ill support for this across language barriers. Besides, most programming languages have a hard time offering a barrier like the one offered by a good old subprocess.

tmpdir.py leverages the widely accessible process abstraction instead.

tmpdir.py aims to be cross-platform and easy to use: tmpdir.py is a small, self-contained Python executable. This makes it easy to just copy tmpdir.py into your source tree and use it. (The Makefile is for testing purposes only.)

Exploratory Examples

The following examples assume that you've added the path to tmpdir.py to your PATH environment variable.

Prefixing your command with tmpdir.py will change working directory to the created temporary directory and execute the command in there:

~$ tmpdir.py bash
/tmp/tmpPOFIGL$ exit
~$ tmpdir.py pwd
/tmp/tmp7x_3Qj
~$ file /tmp/tmpdJCHRW
/tmp/tmpdJCHRW: cannot open `/tmp/tmpdJCHRW' (No such file or directory)
~$ file /tmp/tmp7x_3Qj
/tmp/tmp7x_3Qj: cannot open `/tmp/tmp7x_3Qj' (No such file or directory)

You can also copy a file or directory (e.g., student submission) into the temporary directory with the -c|--copy argument:

~$ tmpdir.py --copy /etc/passwd bash
/tmp/tmpLVfhmy$ ls
passwd
/tmp/tmpLVfhmy$ diff -u passwd /etc/passwd
/tmp/tmpLVfhmy$

Changing the working directory might be intrusive to your scripts, so there is a -k|--keepwd option. To get a hold of the path to the working directory, you either list the special argument name %%TMPDIR, or use the -e|--env argument to store it in a TMPDIR environment variable.

This means that the following commands have a similar effect

~$ tmpdir.py --keepwd echo %%TMPDIR
/tmp/tmpfSuRru
~$ tmpdir.py --keepwd --env bash -c "echo \$TMPDIR"
/tmp/tmp6j4SWa
~$

The argument %%TMPDIR is welcome to appear more than once in the argument list.

You can mandate the parent directory of your temporary directory using the -d|--dir argument, and the prefix and postfix of the directory name using the -p|--prefix and -s|--suffix arguments.