Deletes empty directories and prints an error if directory is not empty.

find largest file in /var

I have a bash alias for this command line and find it useful for searching C code for error messages.

The -H tells grep to print the filename. you can omit the -i to match the case exactly or keep the -i for case-insensitive matching.

This find command find all .c and .h files

Change your wallpaper every thirty minutes (or however long you like, I suppose) to a randomly selected image in a directory and subdirectories. Bear in mind this is not safe to use if anyone else has write access to your image directory.

Clone linux installation.

Copy every file from current directory to destination preserving modification time.

Have a grudge against someone on your network? Do a "find -writable" in their directory and see what you can vandalize! But seriously, this is really useful to check the files in your own home directory to make sure they can't inadvertently be changed by someone else's wayward script.

By time thumbnail images in ~/thumbnails take up too much space, this command will help deleting old ones.

Find options explained:

-type f : find files only, not directories

-atime +30 : last accessed more than 30 days ago

This is useful if you have a collection of files in folders (for example, a bunch of .zip files that are contained in folders) and you want to move them all to a common folder.

Can be used for other commands as well, replace rm with ls.

It is easy to make this shorter but if the filenames involved have spaces, you will need to do use find's "-print0" option in conjunction with xargs's "-0" option. Otherwise the shell that xargs uses to execute the "rm" command line will treat the space as a token separator, thereby treating the name as two (or more) names.

Ever wanted to find the most recently modified files, but couldn't remember exactly where they were in a project directory with many subdirectories? The "find" command, using a combination of "-mtime -N" and "-depth -D" can be used to find those files. If your directory structure isn't very deep, just omit the "-depth -D", but if your directory structure is very deep, then you can limit the depth of the traversal using "-depth -D", where "D" is the maximum number of directory levels to descend.

Takes filenames and directory names and replace space to '_'.

NOT MINE! Taken from hackzine.com blog.

It creates a tree-style output of all the (sub)folders and (sub)files from the current folder and down(deeper)

Quoting some of hackzine's words

"Murphy Mac sent us a link to a handy find/sed command that simulates the DOS tree command that you might be missing on your Mac or Linux box. [..split...] Like most things I've seen sed do, it does quite a bit in a single line of code and is completely impossible to read. Sure it's just a couple of substitutions, but like a jack in the box, it remains a surprise every time I run it."

Run this in the directory you store your music in.

mp3gain and vorbisgain applies the ReplayGain normalization routine to mp3 and ogg files (respectively) in a reversible way.

ReplayGain uses psychoacoustic analysis to make all files sound about the same loudness, so you don't get knocked out of your chair by loud songs after cranking up the volume on quieter ones.

This example summarize size of all pdf files in /tmp directory and its subdirectories (in bytes).

Replace "/tmp" with directory path of your choice and "\*pdf" or even "-iname \*pdf" with your own pattern to match specific type of files. You can replace also parameter for du to count kilo or megabytes, but because of du rounding the sum will not be correct (especially with lot of small files and megabytes counting).

In some cases you could probably use sth like this:

But be aware that this second command CANNOT count files with spaces in their names and it will cheat you, if there are some files matching the pattern that you don't have rights to read. The first oneliner is resistant to such problems (it will not count sizes of files which you cant read but will give you correct sum of rest of them).