Shell: Retrieve empty directories

$ find -type d -empty

Linux: Dell Server / Desktop / Laptop Find Out Service Tag Command

Type the command as follows as root user:

# dmidecode | grep --color -i serial

or

# dmidecode -t 1

Referência: cyberciti.biz/faq/linux-find-dell-service-tag-command

Shell: Count Number of Characters in a String

x="This is a test"
y="${x//[^s]}"
echo "$y"
echo "${#y}"

To match both 's' and 'S', enter:

x="This is a test. S"
y="${x//[^s|S]}"
echo "${#y}"

Multimidia: Adjust vol/gain on ffmpeg transcoding

ffmpeg -i input.mp4 -ab 192 -ar 44100 -vol 512 output.mp3

256, no change. 128, decrease twice. 512, increase twice.

Perl: Split s String into lines

How to split a string into lines while preserving the trailing "\n":
my @a = split(/^/, $text);

Perl: How to capture STDOUT and the exit code

Capture the exit code but not STDOUT:
$status = system("command");

Capture STDOUT but not exit status:
$output = `command`;

Shell: Find and remove dead links

$ find -L -type l -exec rm -f {} \;