I'm Heading Up To Bed

There are several ways to do this, but my Google-fu may be weak because it took me much too long to figure this out.

I want to recursively delete directories with a specific name (or names) within directory structure, UNLESS the matched directory contains a sentinel file.

In my case I want to make a C# directory structure “cleaner-than-clean” by removing all ‘bin’ and ‘obj’ directories, leaving just the user-generated files behind.  This is pretty easy to achieve:

#!/bin/env bash

dir=/path/to/project

find $dir -type d \
    \( -name 'bin' -o -name 'obj' \)
    -print

This says “find things under $dir that are directories (-type d) and are named either ‘bin’ (-name 'bin') or (-o) named ‘obj’ (-name 'obj').  The parentheses force the two -name statements to be considered as a single condition, so the effect is to return true if either item matches. If the final result is true then print the path.

Notice that I’ve escaped (\) the parentheses because I’m using bash. Most UNIX shells do require these to be escaped, but yours may not. I’ve also terminated each line by escaping it. A single-line command may be spread over several lines this way, making it easier to read.

‘bin’ is also the conventional name for a directory of non-build executables, like helper scripts.  I do have some, including this cleaner-than-clean cleaning script that I’m working out, and don’t want to delete those by accident. The above command would find them, if they were in the directory tree.

find allows you to prune (-prune) the search tree, ignoring selective directories, according to certain criteria but it doesn’t support the concept of peeking into sub-directories. Bummer.

You may, however, execute independent commands (-exec) and use the results of those commands to affect find‘s parameters, including -prune. We can exec the test command, which can tell us if our sentinel file exists.

#!/bin/env bash

dir=/path/to/project
sentinel=.keep

find "$basedir" \
    -type d \
    \( -name bin -o -name obj \) \
    ! -exec test -e "{}/$sentinel" ';' \
    -print

The new line executes test to see if the current path ({}) contains a file called $sentinel (I’ve defined $sentinel to be .keep but any filename will do), which returns true if it exists. The line is negated (!) so if the sentinel is found further actions are skipped.

The final step is to actually delete the directory. We call rm -Rf (-R = recursive, -f = force) because we just want the whole thing gone, no questions asked. The trailing plus (+) tells find that rm can accept multiple paths in a single call, rather than calling rm once for each path.

#!/bin/env bash

dir=/path/to/project
sentinel=.keep

find "$basedir" \
    -type d \
    \( -name bin -o -name obj \) \
    ! -exec test -e "{}/$sentinel" ';' \
    -print \
    -exec rm -Rf '{}' \+