Category Archives: Linux

Lets assume you have a CA certificate “ca.crt” that you want your system or utilities like curl to trust then you can do the following:

Copy the CA certificate to /etc/pki/ca-trust/source/anchors/

sudo cp ca.crt /etc/pki/ca-trust/source/anchors/

Then you can run the following command to update Fedora’s local CA store.

sudo update-ca-trust

Now you system and tools like curl will trust certificates signed by this CA.

Verify that SSL connection is trusted using curl :

Lets say you have a webserver server whose certificate was signed by the above root CA and the signed certificate is already uploaded to the webserver. You can verify that your Fedora client trusts the certificate using curl.

curl -vvv https://test-server-fqdn.com

In the above curl command, I am passing the verbose flag -vvv which is optional. It is handy for troubleshooting purposes SSL issues.

If the connection is trusted, the SSL connection should work and you would see a message such as below from the curl outputs:

* server certificate verification OK

Note: This was tested on Fedora 31.

Source/References:

https://serverfault.com/questions/394815/how-to-update-curl-ca-bundle-on-redhat
https://www.linux.org/docs/man8/update-ca-trust.html

Linux, Programming

Run bash script from a Perl script

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To run a bash script (Example: bash-script.sh) from inside a perl script, you could use the following syntax:

system("sh", "bash-script.sh")

Note: Here, once the bash script completes execution it will continue with the execution of the perl script.

Example:

Perl Script: perl-script.pl
Bash Script: bash-script.sh

Below is a perl script “perl-script.pl” which calls an external bash script “bash-script.sh”.

#!/usr/bin/perl
use strict;
use warnings;

print "Running parent perl script. \n";
print "Starting to call external bash script\n";

# Sample Argument to be passed to the bash script
my $my_arg = "ARG1";

# With arguments - pass them inside quotes seperated by commas 
system("sh", "bash-script.sh","$my_arg");

print "Back to parent perl script\n";

Below is the sample “bash-script.sh” which prints the variable.

#!/bin/bash
echo "---Start of Bash script---"

a=$1
echo "Argument from Perl script is" $a

To test, execute the perl script:

./perl-script.pl

Credits/References
https://stackoverflow.com/questions/3200801/how-can-i-call-a-shell-command-in-my-perl-script

Linux, Technology

How to fix print_req_error: I/O error, dev fd0, sector 0 error

2 Comments

After a fresh install of Ubuntu, my terminal was being flooded with “print_req_error: I/O error, dev fd0, sector 0” error.

This is because, your kernel thinks you have a floppy disk fd0, but cant find one. To fix this issue, you can run the following in your terminal:

sudo rmmod floppy
echo "blacklist floppy" | sudo tee /etc/modprobe.d/blacklist-floppy.conf
sudo dpkg-reconfigure initramfs-tools

EDIT: Thanks @Joanmi for your comment (For the noticing the issue with sudo command.)

Misc: If you are deploying a new virtual machine, you can avoid this issue by deleting the Floppy Disk drive.

Source: StackOverflow

Linux, Technology

View progress when using dd command

Tech Antidote

Category Archives: Linux

Update CA certificate store in Fedora to trust a root CA certificate

Run bash script from a Perl script

How to fix print_req_error: I/O error, dev fd0, sector 0 error

View progress when using dd command

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