Linux Tips
This is just a collection of notes for various projects I am working on. The categories of notes are at the top nav bar.
Remove a File with a Dash (-) in the Beginning
To remove file in Linux that has a hyphon or dash in front of it just prefix it with "./". For example:
rm ./-testfile
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Reset SSH password on OctoPrint
1. power off the pi, remove the MicroSD card, and put that in a PC.
2. Then in the drive called "boot", create a file named "octopi-password.txt"
3. In that text file ("octopi-password.txt") you only need the password you want to set for the "pi" user, nothing else. So it will be one word only in this file.
4. Now take the MicroSD out of the PC, install it in the pi and boot it.
5. You can now log in again using SSH, with username "pi" and the password you set in the file "octopi-password.txt".
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View Logs of Last Boot
To use journalctl to view the logs of the last reboot use the following:
journalctl --boot=-1
This command is handy for viewing logs right before a crash. Do the above command then use shift-g to go to the bottom of the list.
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Find History of RPMs
To find the install history of a specific RPM do the following:
rpm -q --last
To find the install history of all RPMs do the following:
rpm -qa --last
NOTE: This will not sort them by install date.
Tags
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Test STARTTLS SMTP Connection
Run the following command to connect
openssl s_client -connect {server}:{port} -starttls smtp
Then find out what authentication is supported. It should now show "AUTH LOGIN" now that you have an encrypted connection:
ehlo {domain.com}
If you see "AUTH LOGIN" in the list then do the following:
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Common firewall-cmd Examples
List all zones:
firewall-cmd --list-all-zones
List all active zones:
firewall-cmd --get-active-zone
To add a host or network to allow all connections from:
firewall-cmd --permanent --zone=trusted --add-source=10.10.10.10
Add a service to be allowed from anywhere:
firewall-cmd --permanent --add-service=smtp
When you run firewall-cmd with the "--permanent" it will not be active until the dameon is reloaded. Do the following to make them active:
firewall-cmd --reload
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Get epoch with Date Command
Here is a quick way to get the current epoch with the date command:
date +%s
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Fix Fn Keys on ASUS Laptops
If you find your Fn keys don't work like volume up/down try the following:
su - echo asus-nb-wmi > /etc/modules-load.d/asus-nb-wmi.conf reboot
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Checking for Bad Blocks on a Hard Drive in Linux
In Fedora, the badblocks program is part of the e2fsprogs program. You probably already have that installed. But in case you don't do the following:
yum install e2fsprogs
To just see the bad blocks the following to do a non-destructive read/write test:
badblocks -nvs /dev/sda
To generate generate a list of the bad blocks do the following:
badblocks -nv /dev/sda > badblocks.txt
Now you can mark the bad blocks found with the following: