General Linux Tips

• Server Investigations
• Cleanup Invalid MP3 Files

Server Investigations

Low Disk Space

Running out of disk space can cause all sorts of havoc.

Get list of directories & files that are taking up the most space. This checks from the current dir, but replace the * with a specific dir to check it specifically.

du -hsx * | sort -rh | head -10 

 

Find Duplicate Processes

If you have a shell script that may pile up with too many duplicate processes running, you can find which scripts have duplicates running with this command:

ps aux | sort --key=11 | uniq -c -d --skip-fields=10 | sort -nr --key=1,1

SELinux

If you're using SELinux, the following command will list things getting blocked by SELinux to help you find potential misconfigurations:

grep -E 'setroubleshoot|preventing' /var/log/messages

Cleanup Invalid MP3 Files

1. Install mp3check
   
   1. Probably already available in your distro. Example: sudo apt install mp3check
2. Scan a directory of MP3 files with: mp3check -erBR3 "SOME_DIR"
   1. This only scans files and reports issues, it does not make any changes
   2. This is recursive. Remove the lowercase -r to not dive into subdirectories
   3. -B causes it to allow variable bitrate files. If your player doesn't support VBR, remove this flag to identify files that are VBR. Note: mp3check cannot convert VBR to CBR, you need tore-encode for that.
3. Fix files with command: mp3check -r3 --cut-junk-start --cut-junk-end "SOME_DIR"
   1. This will write changes to the files stripping out the invalid chunks. The file modified time will be updated

Notes:

• The recursive option does not appear to work properly and only seems to go 1 directory deep
• The Dirname handling seems unusual. You may need to use a /* at the end for it to scan the entire dir 

Example cleanup output: