Shell Stuff: Easy File Cleanup

World War I Memorial Park, North Attleboro, MA

Applications can leave their junk files all over the place. While I appreciate that all of the .swp, .retry, and "conflict" files are there to help me when things go wrong… sometimes I just want to clean up my file system. So… here is a simple string of commands I often use to declutter my files.

DISCLAIMER: I know there are MANY ways to accomplish this. The method described in this post is to share one efficient solution I use, that might help someone that currently knows zero.

The commands

First, lets quickly meet the commands we will be using:

Find

find is a classic UNIX command that searches for files in a directory hierarchy. By default, it writes out the file path for each file/directory that it finds.

Example:

➜  tree
.
├── dirA
│   ├── file3
│   ├── file4
│   └── file5
├── dirB
│   └── file6
├── file1
└── file2

2 directories, 6 files

➜  find .
.
./file2
./file1
./dirB
./dirB/file6
./dirA
./dirA/file5
./dirA/file4
./dirA/file3

Grep

Another classic. Basically, grep searches for a pattern in each file provided. In addition to files, it can search text passed through a pipe (this is important for our use, but more on that later).

Example:

➜  cat file1
This is a fake file
with a few lines of content.

However, I want search for something
without opening it...

Secret: 12345

I wonder if I will be able to get it...


➜  grep Secret file1
Secret: 12345

Command Substitution

Lastly, command substitution is taking one command, and using it’s output as part of another command. Traditionally, this was done by calling the substitution command `inside backticks`, but it is now preferred to use $(COMMAND) instead of backticks.

Example:

➜ echo I am at: `pwd`
I am at: /tmp/demo

or (preferred):

➜ echo I am at: $(pwd)
I am at: /tmp/demo

Pipes

An unix pipe (|) directs the output of one command, to be used as the input for another command. Pipes can be used to chain together several commands, forming a pipeline.

Example:

The output of ls can be fed as input to wc (word count) to create a pipeline command that returns the number of files/directories in the current directory.

➜ ls
dirA  dirB  file1  file2

➜ ls | wc -l
4

Putting It All Together

Now that we know all the parts, how does it all fit together? One particular shell chain I find convenient is pairing find and grep to recursively get all the paths of a particular file type, and then use it in a command substitution to pass that result on to another command (such as rm).

COMMAND $(find . | grep SEARCHSTRING)

This is the combination I use to clean up my directories. While working on writing ansible playbooks, I can generate a few *.retry files, as well as some *.swp files from editing in vim.

Example:

➜ find . | grep .retry          ## Find *.retry files
./file1.retry
./dirA/file5.retry
./dirA/file3.retry

➜ rm $(find . | grep .retry)    ## Delete *.retry files

➜ find . | grep .retry          ## Check that they were deleted

➜

Summary

That’s it. A small post for a simple but powerful command line set. If you haven’t used this team of commands before, give it a try sometime! Have fun!