Tag: bash

Linux: Getting Drive Serial Number

[lisa@FVD01 /mnt/lisa/]# smartctl -i /dev/sdc
smartctl 7.5 2025-04-30 r5714 [x86_64-linux-6.15.7-200.fc42.x86_64] (local build)
Copyright (C) 2002-25, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Model Family: Western Digital Red (CMR)
Device Model: WDC WD40EFRX-68N32N0
Serial Number: WD-WCC7K4HY5TKD
LU WWN Device Id: 5 0014ee 2b9a3d0c5
Firmware Version: 82.00A82
User Capacity: 4,000,787,030,016 bytes [4.00 TB]
Sector Sizes: 512 bytes logical, 4096 bytes physical
Rotation Rate: 5400 rpm
Form Factor: 3.5 inches
Device is: In smartctl database 7.5/5706
ATA Version is: ACS-3 T13/2161-D revision 5
SATA Version is: SATA 3.1, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is: Tue Dec 2 17:24:27 2025 EST
SMART support is: Available – device has SMART capability.
SMART support is: Enabled

2025-12-02 17:24:27 [root@FPP01 /mnt/MythAndZoneminder/]# smartctl -i /dev/sda
smartctl 7.5 2025-04-30 r5714 [x86_64-linux-6.15.7-200.fc42.x86_64] (local build)
Copyright (C) 2002-25, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Model Family: Western Digital Red (CMR)
Device Model: WDC WD40EFRX-68N32N0
Serial Number: WD-WCC7K7JZSZ0E
LU WWN Device Id: 5 0014ee 264576d5e
Firmware Version: 82.00A82
User Capacity: 4,000,787,030,016 bytes [4.00 TB]
Sector Sizes: 512 bytes logical, 4096 bytes physical
Rotation Rate: 5400 rpm
Form Factor: 3.5 inches
Device is: In smartctl database 7.5/5706
ATA Version is: ACS-3 T13/2161-D revision 5
SATA Version is: SATA 3.1, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is: Tue Dec 2 17:24:38 2025 EST
SMART support is: Available – device has SMART capability.
SMART support is: Enabled

 

Quick sed For Sanitizing Config Files

When sending configuration files to other people for reference, I like to redact any credential-type information … endpoints that allow you to post data without creds, auth configs, etc. Sometimes I replace the string with REDACTED and sometimes I just drop the line completely.

Make a copy of the config files elsewhere, then run sed


# Retain parameter but replace value with REDACTED
sed -i 's|http_post_url: "https://.*"|post_url: "REDACTED"|' *.yaml

# Remove line from config
sed -i '/authorization: Basic/d' *.yaml

Docker Registry: Listing Images and Timestamps

I wanted a quick way to verify that Docker images have actually been pushed to the registry … I’m using Distribution, and only wanted to report on images that start with sample (because the repository is shared & I don’t want to read through the very long list of other people’s images)

#!/bin/bash

registry="registryhost.example.net:5443"
authHeader="Authorization: Basic AUTHSTRINGHERE"

# List all repositories
repositories=$(curl -s -H "$authHeader" https://$registry/v2/_catalog | jq -r '.repositories[]')

for repo in $repositories; do
  # Check if the repository name starts with "npm"
  if [[ $repo == sample* ]]; then

    # List all tags for the repository
    tags=$(curl -s -H "$authHeader" https://$registry/v2/$repo/tags/list | jq -r '.tags[]')

    for tag in $tags; do

      # Get the manifest for the tag
      manifest=$(curl -s -H "$authHeader" -H "Accept: application/vnd.docker.distribution.manifest.v2+json" https://$registry/v2/$repo/manifests/$tag)

      # Extract the digest for the config
      configDigest=$(echo $manifest | jq -r '.config.digest')

      # Get the config blob
      configBlob=$(curl -s -H "$authHeader" https://$registry/v2/$repo/blobs/$configDigest)

      # Extract the last modified date from the config history
      lastModifiedDate=$(echo $configBlob | jq -r '[.history[].created] | max')

      echo -e "$repo\t$tag\t$lastModifiedDate"
    done
  fi
done

RSync to Mirror Local Files

The rsync utility was meant to be used to sync files across the network — to or from an rsync server. For some time, I had a group of friends who shared documents off of my rsync server. Anyone with access could run an rsync command and sync their computer up with the group’s documents. With the advent of online file storage and collaborative editing, this was no longer needed. But I still use rsync to make sure my laptop has a local copy of a folder on the server. Mount /path/to/folder/contents/to/copy to the SMB or NFS share, and the following rsync command ensures the laptop’s /path/to/where/contents/should/be/placed has an exact mirror of the contents of the server folder

rsync –archive –verbose –update –delete “/path/to/folder/contents/to/copy/” “/path/to/where/contents/should/be/placed/”

–archive is a grouping of:
-r recursive
-l copy symlinks
-p preserve permissions
-t preserve modification timestamps
-g preserve group
-o preserve owner
–devices preserve device files (su only)
–specials preserve special files

Counting Messages in All Kafka Topics

For some reason, I am given a lot of Kafka instances that no one knows what they are or what they do. The first step, generally, is figuring out if it does anything. Because a server that no one has sent a message to in a year or two … well, there’s not much point in bringing it up to standard, monitoring it, and such. My first glance analysis has been just counting all of the messages in all of the topics to see which topics are actually used — quick bash script to accomplish this (presuming a Kafka broker is on port 9092 of the host running the script)

strTopics=$(./kafka-topics.sh --list --bootstrap-server $(hostname):9092)

SAVEIFS=$IFS   
IFS=$'\n'      
arrayTopics=($strTopics)
IFS=$SAVEIFS   

for i in "${arrayTopics[@]}"; do iMessages=`./kafka-console-consumer.sh --bootstrap-server $(hostname):9092 --topic $i --property print.timestamp=true --from-beginning --timeout-ms=10000 2>&1 | grep "Processed a total of"`;         echo "$i     $iMessages"; done

Logstash, JRuby, and Private Temp

There’s a long-standing bug in logstash where the private temp folder created for jruby isn’t cleaned up when the logstash process exits. To avoid filling up the temp disk space, I put together a quick script to check the PID associated with each jruby temp folder, see if it’s an active process, and remove the temp folder if the associated process doesn’t exist.

When the PID has been re-used, this means we’ve got an extra /tmp/jruby-### folder hanging about … but each folder is only 10 meg. The impacting issue is when we’ve restarted logstash a thousand times and a thousand ten meg folders are hanging about.

This script can be cron’d to run periodically or it can be run when the logstash service launches. 

import subprocess
import re

from shutil import rmtree

strResult = subprocess.check_output(f"ls /tmp", shell=True)

for strLine in strResult.decode("utf-8").split('\n'):
        if len(strLine) > 0 and strLine.startswith("jruby-"):
                listSplitFileNames = re.split("jruby-([0-9]*)", strLine)
                if listSplitFileNames[1] is not None:
                        try:
                                strCheckPID = subprocess.check_output(f"ps -efww |  grep {listSplitFileNames[1]} | grep -v grep", shell=True)
                                #print(f"PID check result is {strCheckPID}")
                        except:
                                print(f"I am deleting |{strLine}|")
                                rmtree(f"/tmp/{strLine}")

Using urandom to Generate Password

Frequently, I’ll use password generator websites to create some pseudo-random string of characters for system accounts, database replication,etc. But sometimes the Internet isn’t readily available … and you can create a decent password right from the Linux command line using urandom.

If you want pretty much any “normal” character, use tr to pull out all of the other characters:

'\11\12\40-\176'

Or remove anything outside of upper case, lower case, and number characters using

a-zA-Z0-9

Pass the output to head to grab however many characters you actually want. Voila — a quick password.