Handy Bash / Command Line Commands

command_line.md

Count Files Matching A Certain Pattern

Option 1 - recursive

ls -1f | grep wav | wc -l

Option 2 - only current dir

find . -maxdepth 1 -name "*wav" | wc -l

Rename A File

mv worker.sh mp3_worker.sh

Count Lines in a File

wc -l results.txt 

Remove Duplicate Lines from A File

sort -u results.txt 

Copy Files from Remote Server to Local Machine (ec2)

scp -i "your_ec2_key.pem" -r ec2-user@ec2-xx-xx-xx-xxx.compute-1.amazonaws.com:/home/ec2-user/files ~/Desktop/your_dir/

Loop Over Files and Execute Command Writing Output to Text File (example uses aubio.org music software)

for f in *.mp3
do
	var=$(aubio tempo $f)
        echo $var ", $f"
        echo $var ", $f" >> results.txt
done

Create a Copy of A file

cp mp3_worker.sh wav_worker.sh

Combine Multiple Text Files

• (note >> means append, > will overwrite existing in all_results.txt)

cat results.txt wav_results.txt >> all_results.txt